What’s the pollen outlook this year?

Posted on 22 March, 2024 by Met Office Press Office

The Met Office launches this year’s Pollen Forecast today (Friday 22 March) which will run until mid-September.

One in five people in the UK suffer from hay fever, meaning spring can be the start of watering eyes, runny noses and keeping a keen eye on the pollen forecast, which is now available and provides a look at the pollen amounts and types in the air for the next five days.

This February was the warmest on record for England and Wales and winter too has followed this wet and warm pattern. This has an influence on the pollen season ahead.

Yolanda Clewlow is the Met Office’s Relationships Manager for Health and Air Quality, and the UK Pollen Forecast Manager. She said: “We’re constantly monitoring what’s in the atmosphere and what might be coming in terms of pollen in the air. We look at a very broad picture for the pollen outlook, including the weather in the previous year when pollen is formed on some plants to make a judgement on how heavy a season might be for pollen release. Rain, wind, temperature and sunshine all affect how much pollen will be produced and how much it will be dispersed.”

The Met Office works with the University of Worcester to monitor pollen levels. There are many factors at play when predicting levels, with much depending on how much pollen has formed on the plants and the weather at the time of release. Most people are allergic to grass pollen, which is generally released around mid-May to July.

Yolanda continued: “In terms of birch pollen, we are seeing the first grains in the atmosphere in the most southerly and easterly counties but overall, there’s currently generally low levels for tree pollen due to changeable conditions. We expect the season to be of mild to average severity depending on in-season weather.

“Grass pollen could start early, with some pollen airborne from late April. Average severity is most likely, but this will largely depend on the weather in April and early May. Warm sunshine and some rain is needed for good grass growth and pollen production. Dry conditions would inhibit growth.”

There are millions of hay fever sufferers across the UK. The Met Office pollen forecasts provide vital information to help reduce the impact pollen has on their health. 

Emma Rubach is the Head of Health Advice at Asthma + Lung UK. She said: “High pollen levels can be dangerous for people with lung conditions like asthma or COPD (chronic obstructive pulmonary disease), triggering symptoms such as breathlessness, coughing or wheezing. and could lead to hospitalisation or a potentially life-threatening asthma attack.

“To protect themselves, we would advise people with hay fever to use their preventer inhaler every day as prescribed, if they have one, and always have their reliever inhaler with them, in case symptoms do arise.  

“If you’re allergic to pollen, using steroid nasal spray every day can also help, together with non-drowsy antihistamine tablets to help reduce the allergic reaction. It is also a good idea to check pollen and air pollution forecasts in their local area, so they can avoid going outdoors as much as possible on high pollen days.”    

The three types of pollen

The pollen season generally has three main pollen type phases:

  • Tree pollen – late March to mid-May
  • Grass pollen – mid-May to July (most people are allergic to grass pollen)
  • Weed pollen – end of June to September

“The first thing to do is to make sure you understand the type of pollen you’re allergic to and monitor the forecast,” said Yolanda.  

“That way, you know when the very high days of pollen are coming and you can take precautions to try and avoid the pollen. It’s not possible to avoid it altogether though so for some, it’s about taking that preventative medication and planning your day to try and avoid being out in the pollen at the peak times.”

Pets can also be affected by hay fever and in severe cases, vets can often prescribe medication to help furry friends through the summer.

Advice on dealing with hay fever is available as part of WeatherReady with the Met Office.

Pollen levels and climate change

With global temperatures increasing, the pollen season in the UK isn’t immune to the effects of a changing climate. Climate models suggest an increasing likelihood of warmer, wetter winters and hotter drier summers, which will influence the release of pollen into the atmosphere.

A study conducted by the University of Worcester looked at pollen trends in the UK over the last 26 years to better understand the relationship between these trends and meteorological factors. It examined a range of UK pollen sites, with a focus on the key pollen types: grass, birch and oak. 

Dr Beverley Adams-Groom, Senior Pollen Forecaster at the University of Worcester and lead author of the study, said: “Birch tree pollen is showing a trend for increasing severity, particularly in the Midlands region, but grass pollen is not showing an increase over time. Seasons for all pollen types are tending to start earlier and earlier but there is no evidence that season duration is changing. Where changes are occurring, these are largely related to the effects of global warming, with similar patterns seen from research in nearby countries.”

Get pollen alerts directly to your phone on the Met Office app, or visit the pollen forecast on the Met Office website.

 

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Met Office scientists protecting our forests from pests and pathogens

Posted on 21 March, 2024 by Met Office Press Office

Today is the United Nations International Day of Forests, and in this blog post we explore the importance of this work.

The Climate and Plant Biosecurity Climate Service, funded by the Department for Environment, Food and Rural Affairs (Defra), is a collaboration between the Met Office’s Vegetation-Climate Interactions team, Defra’s Plant Health Risk and Horizon Scanning team, the University of Exeter, Fera Science, the University of Warwick, Forest Research and The Royal Botanic Gardens, Kew.

Oak processionary moth caterpillars. This species is a non-native pest of woodlands. Picture: Adobe Stock.

Since 2006 the non-native and invasive Oak Processionary Moth has been spreading across England and Wales. Picture: Adobe Stock

The aim of the service is to provide analyses, tools and guidance to help manage the climate-related risks to UK plants, particularly trees and forests, from plant pests and pathogens.

Pest and pathogen outbreaks

Pests and pathogens present serious risks to our trees and forest habitats as well as the ecosystem services they provide. The number of new pest and pathogen outbreaks affecting trees has increased rapidly in recent years (see table, Source: Forestry Commission).

Year (since 1971)             New tree pest or pathogen outbreak

  • 1971      Dutch elm disease
  • 1983      Great spruce bark beetle
  • 1984      Phytophthora alni
  • 1995      Gypsy moth
  • 1997      Dothistroma needle blight
  • 2002      Phytophthora ramorum
  • 2002      Horse chestnut leaf miner
  • 2003      Phytophthora kernoviae
  • 2005      Bleeding canker of horse chestnut
  • 2006      Oak processionary moth
  • 2006      Phytophthora pseudosyringae
  • 2007      Pine tree lappet moth
  • 2010      Acute oak decline
  • 2010      Phytophthora lateralis
  • 2012      Ash dieback
  • 2012      Asian longhorn beetle
  • 2012      Sweet chestnut blight
  • 2012      Phytophthora austrocedri
  • 2014      Phytophthora sikiyouensis
  • 2014      Sirococcus tsugae
  • 2015      Oriental chestnut gall wasp
  • 2017      Elm zigzag sawfly
  • 2018      Eight toothed spruce bark beetle
  • 2021      Phytophthora pluvialis

Climate (variability and change) influences pests and pathogens in many ways, including i) the timing of life cycle events (such as emergence from egg to caterpillar), ii) the spatial distribution and spread, and iii) the introduction and establishment of non-native species.

Tools to help manage UK plant biosecurity

The UK Climate-Pest Risk Web Tool is one of the tools that has been developed by Met Office scientists Neil Kaye and Deborah Hemming (Vegetation-Climate Interactions team) in collaboration with biosecurity and forestry experts at Defra, Forest Research, Fera Science and the University of Warwick. It integrates ecological knowledge and models of known temperature thresholds for different pests/pathogens, with up-to-date climate observation datasets from the Met Office National Climate Information Centre.

Deborah Hemming, Scientific Manager of the Vegetation-Climate Interactions team at the Met Office, who leads this climate service, notes: “When tree pests and diseases become established, they can wreak havoc on our woodlands. Commercial forestry can be affected hugely, but they also affect the landscapes of our islands which many people love and cherish. In the 1970s, Dutch Elm Disease killed most of the UK’s stately elm trees with those plants remaining being small stands in isolated sections of hedgerow. Similarly, Ash Dieback since 2012 has decimated ash trees with similar devastating effect.

“When trees die, especially native broadleaf trees, there are impacts on landscape and wildlife. And in times of climate change there is also a reduction in the availability of carbon stocks because trees provide a hugely valuable ecosystem service by drawing down atmospheric carbon and locking it away. By joining forces with experts in plant biosecurity at Defra, ecological modelling at University of Exeter, forestry at Forest Research and ecological systems at Royal Botanic Gardens, Kew, we are able to provide scientifically robust and useful research, tools and services to help protect UK trees and forests now and into the future.”

The tool enables users to easily estimate the timings and locations of pest outbreaks across the UK, and inform actions to assess, survey, monitor and eradicate plant pests, helping to enhance UK plant biosecurity.

Simon Toomer, Curator of Living Collections at Royal Botanic Gardens, Kew, says: “As we develop strategies and plans to adapt and prepare our tree and shrub collections for changing climatic conditions, one of the most complex and least understood threats is that from pests and diseases. This research is going to help us understand how changes in general climate variables translate into changes in the specific conditions experienced by pest species, and how we may adapt our management accordingly.”

Healthy ash trees form an important part of the UK's tree canopy. Isolated trees are also a feature of hedgerows. Picture: Adobe Stock

Healthy ash trees form an important part of the UK’s tree canopy. Isolated trees are also a feature of hedgerows. Picture: Adobe Stock

Improving monitoring and modelling of microclimates

Pests and pathogens respond to microclimates within the habitats where they live. To improve the estimates of pest/pathogen risks, ecological modellers at the University of Exeter have developed mechanistic microclimate models to estimate temperature and humidity within relevant habitat locations e.g., under tree canopies, inside tree trunks or buried at various depths within the soil. In these habitats, microclimates can vary by 40-50°C and be significantly different to conditions observed at weather stations.

Ilya Maclean, Professor of Global Change Biology at the University of Exeter, says: “It is important to understand the climate as pests and pathogens experience it. This can be very different from the conditions measured by a weather station. My team is developing models that allow us to do this and the data we are collecting as part of this project will be invaluable in helping us improve our models”.

Daegan Inward, Senior Scientist at Forest Research, explains further: “We know that beetle outbreaks are often associated with sun-warmed stems, and understanding the under-bark microclimate is important to help predict the risk of insect establishment and population growth in Britain.”

Climate change and globalisation

To validate the microclimate models, in February 2024 the Met Office, the University of Exeter, Forest Research and Kew Gardens began a campaign of microclimate monitoring at five sites in different forest habitats across southern England (Cornwall, Dartmoor, Alice Holt, Kew Gardens and Wakehurst). The team installed a series of sensors to monitor temperature within the woodlands and inside tree trunks. The data collected will help improve the understanding and modelling of variations in the pest/pathogen microclimates, and therefore the estimates of biosecurity risks.

Defra Chief Plant Health Officer Nicola Spence said: “Climate change and globalisation are increasing the number and diversity of pests and pathogens we are exposed to, resulting in an ever-growing number of threats. This collaborative effort to develop climate modelling tools and improve our understanding of pest or pathogen climate interactions, will allow us to better plan for and improve our ongoing surveillance and monitoring. This work is crucial to adapt to a changing climate and better understand how the health and resilience of our trees could be at risk.”

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One in 250-year event underway high in the atmosphere.

Posted on 6 March, 2024 by Met Office Press Office

For the first time since records began in the mid 20th century , this extended winter period (November to March) is the first in our observational records to see three Sudden Stratospheric Warming (SSW) events. Met Office research suggests the likelihood of having three SSW events in one winter period is just a one in 250-year chance, although it is more likely to happen during an El Niño winter, such as this winter.

The record of SSW events goes back to the 1950s with the introduction of radiosonde balloons which are used to take observations high in the stratosphere on a routine basis. Since then, there has been typically one SSW every two extended winters. However, there are occasional runs of years with no warming events at all e.g. in the 1990s. There are also winters with two warmings such as the winter of 2009/10.

Professor Adam Scaife, Head of Long-Range Forecasting at the Met Office, said: “Although we have not seen it before, we recently documented the chances of an unprecedented three SSW events happening in one winter. Our research work, using multiple computer simulations, showed that this could occur about once in every 250 winters.”

Professor Scaife added, “Although this is very rare, we also found that the chance of multiple SSW events is increased during El Niño and so the chance of multiple events this winter is raised.”

3rd SSW winter

Forecast pressure for mid-March showing relatively high pressure over Iceland and low pressure over mid latitudes (Units: hPa).

A SSW is a disruption of the normal westerly air flow 10 to 50 km above the earth. This often makes the jet stream meander more, which can lead to the development of a large area of high pressure over northern Europe at the Earth’s surface. This can ‘block’ the Atlantic low-pressure systems which are responsible for the relatively mild, wet and windy weather that often occurs in UK winters. This blocking pattern increases the chance of cold, dry weather in the UK and mild, wet and windy conditions for southern Europe. However, the impacts of an SSW do not always equate to cold weather, for example, we have only seen intermittent drops in temperature around the two SSW events early this winter and typically around 70% of events are associated with a cold snap.

SSW is just one of a number of global drivers that can affect weather in the UK, the current SSW is consistent with the latest long-range outlook for March which suggests a continued increased chance of blocked, high-pressure conditions to the north of the UK and a southward shift in the Atlantic jet stream.

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Wildlife banking on a warm spring

Posted on 1 March, 2024 by Met Office Press Office

Today (1 March 2024) is the first day of meteorological spring. We cannot yet guarantee exactly what this spring will bring, but wildlife will be betting on another warm one, writes Grahame Madge – a Met Office climate spokesman and wildlife enthusiast – ahead of the United Nations’ World Wildlife Day on Sunday.

The red admiral butterfly can now be seen on virtually any warmish day in the UK. Previously it wasn’t an over-wintering species and it only used to occur here in the warmer months as a visitor from further south. Picture: Grahame Madge


For the UK, the five warmest springs since 1884 have all occurred since 2007. Wildlife is responding to this shift towards warmer springs by accelerating their own activities.

An index of spring – compiled from observations of the appearance of key spring wildlife species – is occurring many days earlier now when compared with the first half of last century.

The wildlife spring index shows the timing of biological spring events (the number of days after 31 December) in the UK. From 1891 to 1947 the Royal Meteorological Society provided the data, while from 1998 to 2022 it was provided by the UK Phenology Network (Nature’s Calendar, currently funded by the People’s Postcode Lottery, Postcode Green Trust). The Spring Index is calculated from the annual mean observation date of the following four biological events: first flowering of hawthorn; first flowering of horse chestnut; first recorded flight of an orange-tip butterfly; and first sighting of a swallow.


Already this year, at least one swallow has been reported in southern England; returning from Africa well ahead of the rest of its cohort. I have seen red admiral butterflies, bumble-bees and many chiffchaffs – a small usually summer-visiting songbird – in my corner of Exeter and sections of my walk to work have been lined with primroses. Anecdotally, these sightings are much earlier than I would expect.

However, my ad-hoc sightings in the margins of my dog-eared notebook are backed up by an army of wildlife fans diligently recording species across the UK through the Woodland Trust’s Nature’s Calendar scheme.

The recording of the timing of biological events is known as phenology. Two long-running nature surveys – monitoring four easily recorded species – have revealed that the average of time of appearance of these four species since 1998 is 8.7 days earlier than the average dates in the first part of the 20th Century. This is alarming, but not exceptional as other trends have been recorded too.

The dashed trend line in this graph shows that the UK spring has become more than 1.0°C warmer in the last 100 years.

A new course for the red admiral

The striking red admiral butterfly has always been a familiar visitor to parks and gardens the length and breadth of the UK. It used to be an exclusively migratory butterfly arriving on our shores after crossing the English Channel. But warmer winters are now altering this insect’s behaviour. Our winters are now becoming warm enough for it to overwinter as an adult to emerge on warm days in winter or early spring.

The warming of our climate is leading to a response from nature. The red admiral is an extremely abundant and seemingly adaptable insect, so it is unlikely to suffer any population consequences from this behaviour; at least at a species level. However, you have to wonder about the fate of those individuals encouraged to take their first flight of the year in winter, only to be hit by frost a few days later. What happens to them?  My colleague Dr Mark McCarthy a Met Office climate statistics expert noted: “While frosts and cold spells in winter are falling, the date of first/last frost haven’t actually shifted all that much. So, although there are fewer frosts overall the risk of a ‘false spring’ in winter can increase the exposure to spring frosts later in the season. So, for parts of the environment and the agricultural and horticultural sectors there can be increased frost risks even with a declining trend.”

What happens when nature can’t rely on a warm spring?

Many species are making the most of warmer winters and springs to gain an ecological advantage and make the most of the changing seasons. In fact, they are banking on the UK’s climate statistics showing that winter and spring are becoming warmer, on average. But these trends are derived from seasonal averages of temperatures observed over a standard three-decade period. Occasionally, the actual temperature can be a long way from the long-term average and wildlife can be caught out by a colder-than-average spring. This happened in 2013.

The spring of 2013 was the coldest in the UK in 50 years. Some species were severely impacted. Although not a common event, springs as cold as 2013 happened more frequently in the late 19th and early to mid 20th Century.

The stone-curlew is one of England’s rarest birds, with a small and vulnerable population in southern and eastern England. Picture: Adobe Stock


In 2013 I worked for the RSPB, and we were being besieged by members of the public reporting odd birds turning up in gardens desperate for food and respite from the cold. The greatest concerns for a conservation organisation were the fates of those species whose populations had become severely depleted by other factors. The number one species of worry was for the stone-curlew, a species of wading bird thinly spread across parts of the agricultural landscapes of southern and eastern England. The birds spend the winter around the Mediterranean and arrive back on their nesting sites in early spring. Farmers were reporting numbers of these birds which had succumbed to the cold because of a lack of food. At the time the RSPB’s conservation director Martin Harper said: “I can’t remember a spring like this – nature has really been tested by a prolonged period of very cold weather.”

During parts of March 2013, the average temperature in the UK dipped to their lowest levels.


Climate change is affecting many species of wildlife. Some will adapt and others won’t. But even those with potential to adapt may be confounded by other factors, and populations which are already depleted will be less resilient to climate change impacts.

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The risk of wildfires in a changing climate 

Posted on 1 March, 2024 by Met Office Press Office

Fires can be a natural and positive part of the healthy functioning of many ecosystems. However, the pattern of large or unusual fires – known as wildfires – is changing, and there is scientific consensus that climate change is promoting the conditions on which they depend, such as the frequency and intensity of fire weather.  

Fires mostly result from the interaction between climate conditions (such as temperature, moisture, and lightning), vegetation (fuel availability and dryness) and people (through land-use change, ignition, and suppression), and changes in these factors are leading to shifts in fire patterns in many regions of the world.  

It is widely known that the overall global burned area is decreasing, as explored by one report from Science magazine in 2017. This is mainly driven by land-use change from natural savannah and grasslands to agriculture. However, changes in land use can act as a driver for fires in different areas such as tropical forests, and in other regions such as high-latitude forests wildfires are increasing more in line with fire weather and fire season length. Extreme weather, a warming climate, and a build-up of dried-out vegetation acting as fuel, can also result in fires that are larger, more intense, or more frequent than normal, which can lead to the destruction of habitats (wildlife and vegetation) and negative impacts on society (destruction of infrastructure, displacement of people, and air pollution), as well as impacting carbon sinks. 

A negative cycle 

Wildfires and climate change can be part of a negative cycle. Fires can contribute to climate change through releasing carbon from soils and vegetation but are also affected by climate change through hotter and, in places, drier conditions.  

Climate change can lead to plant life drying out more quicky, which creates more flammable vegetation to burn. In turn, this burning contributes to climate change by the release of carbon and the destruction of natural carbon sinks, such as forests. The effects of climate change on wildfires have been apparent in many regions of the world in recent years. For example, climate change more than doubled the likelihood of extreme fire weather in Eastern Canada in 2023 (WWA), and extreme wildfires are moving into unexpected places – like the Arctic, wetlands, peatlands and rainforests that would not previously have been expected to burn easily (UNEP 2022). The vegetation in these are places is not adapted to fire and these locations also hold huge amounts of carbon. Fire’s overall contribution to the carbon cycle though is complex, including carbon uptake in plant regrowth, phytoplankton blooms in the ocean, storage of burnt carbon in soils, as well as variable effects from aerosols.  

It is important to note that climate change will not impact all environments in the same way. In some areas climate change may lead to changes in precipitation and fuel availability, which may decrease flammability, but in other areas climate change may increase fires (e.g., extreme fires in Europe). Higher temperatures alone will not necessarily lead to more fires in all cases; however, our climate system is finely balanced, and small changes can have significant consequences. At 2 °C of warming, models calculate that more areas globally would be at risk of higher fire danger compared to today. Overall, the changing and warming of the climate has increased the scale, intensity, and impact of extreme events in many regions across the globe. 

Met Office research 

The Climate Science for Service Partnership Brazil (CSSP Brazil) research project aims to build strong partnerships between research institutes in the UK and Brazil. As part of this project, scientists from the UK and South America have worked together to develop a seasonal fire probability forecasting service. This delivers forecasts of fire probability for South America several months in advance and enables communities to prepare for these events and mitigate some of the risks posed.  

Dr Chantelle Burton, climate scientist at the Met Office, said: “We are already seeing the impact of climate change on weather patterns all over the world, and this is disrupting normal fire regimes in many regions. It is important for fire research to explore what is changing, what effect this could have on people and the environment, and what communities need to do to prepare.” 

Follow the #GetClimateReady hashtag on X (formerly Twitter) to learn more about forests and climate change. 

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A precautionary approach required to avoid large-scale collapse of the Amazon forest

Posted on 15 February, 2024 by Met Office Press Office

The Amazon is a complex dynamical system with extraordinarily diverse terrestrial and aquatic ecosystems which are home to more than 10% of Earth’s biodiversity, as well as 40 million people.

It is one of the most critical elements of the Earth’s climate system, with the forest acting as a giant “air-conditioner”, lowering land-surface temperatures and generating rainfall in the region. as well as exerting a strong influence on the atmosphere and circulation patterns, both regionally and globally. It also acts as an important terrestrial carbon sink, absorbing more carbon from the atmosphere than it releases and storing an amount of carbon equivalent to 15-20 years of global CO2 emissions (150-200 Pg C), helping to limit atmospheric concentrations and accelerated global warming.

Pied tamarin
The pied tamarin is one of the world’s most threatened primates. Confined to a small part of the Brazilian Amazon rainforest, the Critically Endangered monkey is affected by several factors, largely linked to deforestation. Picture: Shutterstock

Large parts of the Amazon forest, however, are projected to die within this century due to climate and land-use changes, which could trigger cascading effects and push Earth’s climate to a substantially warmer and unpredictable state. It remains uncertain whether a large-scale dieback of the Amazon could actually happen within the 21st Century though the possibility has raised significant global concern.

A new study led by Dr Bernardo Flores of the Federal University of Santa Catarina and including a team of collaborators from Brazil, Europe and the USA, Critical transitions in the Amazon forest system, has synthesised existing evidence for five potential critical thresholds in the Amazon forest. In the context of climate science, a critical threshold refers to potential tipping points in the earth’s system or related processes which, if passed, can cause sudden, dramatic or even irreversible changes to some of the earth’s largest systems, such as the Antarctic ice sheet or the Amazon rainforest. The resulting socio-economic impacts could be very large, and crossing of one critical threshold may then make others more likely to be crossed. Understanding the impact of tipping points is an important element of climate change risk assessment.

Tipping point potential

Partly funded by the Climate Science for Service Partnership (CSSP) Brazil and AmazonFACE, the study has assessed the existing evidence combined with the most plausible ecosystem trajectories and spatial climatic variability, identifying areas within the Amazon forest with higher tipping point potential by the year 2050. AmazonFACE conducts crucial work on the existence, magnitude and duration of CO2 fertilization in the Amazon, which the new study highlights as a key uncertainty in the Amazon crossing a critical threshold.

Flores said: “Findings show that the forest is becoming increasingly exposed to warming temperatures, droughts, deforestation and fires, even in the west of the region that was previously remote to these pressures.”

Mechanisms that previously maintained the Amazonian forest’s resilience to large-scale tipping points are now weakening, increasing its vulnerability to change. Intensification of climatic variability and disturbance regimes in the region over the coming decades may expose an additional 10 – 47 % of the Amazon forest biome to tipping events. In such scenario, the system could cross the tipping point in accumulated forest loss, triggering a large-scale dieback of the Amazon, and being replaced by either degraded forest, savanna or degraded open-canopy ecosystems. This would result in the region becoming a major source of greenhouse gases rather than a carbon sink, risking efforts to keep global warming below 1.5oC.

Flores continues: “Compounding disturbances are increasingly common within the core of the Amazon. If these disturbances act in synergy, we may observe unexpected ecosystem transitions in areas previously considered as resilient, such as the moist forests of the western and central Amazon.”

Opportunities

However, the study reveals opportunities for action to help reduce the pressures on this iconic system and the essential ecosystem services it provides. Findings suggest a list of thresholds that, if well managed, can help maintain the Amazon forest within a safe operating space, avoiding a catastrophic dieback. These depend on ending forest loss and boosting forest restoration at the local scale, but also on global efforts to reduce greenhouse-gas emissions. The consequences of losing the Amazon forest, or even parts of it, imply that we must follow a precautionary approach.

Co-author Professor Richard Betts MBE, of the Met Office, comments: “After 25 years of research, the potential for a tipping point in the Amazon has gone from a theoretical concept to a real and imminent threat. We still have the chance to avoid it by both stopping deforestation and halting global warming by phasing out fossil fuels, but both of these need to happen urgently.”

Article: Flores et al. (2024) “Critical transitions in the Amazon forest system”, Nature, DOI:10.1038/S41586-023-06970-0.

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Our changing weather patterns: a tale of abrupt transitions

Posted on 5 February, 2024 by Met Office Press Office

Our weather is notoriously changeable – that is partly what makes it one of the nation’s talking points. But peering through the statistics a striking pattern emerges: one where the weather oscillates abruptly between different and contrasting phases lasting for a while before the next phase in the sequence begins to dominate.

Let’s look at January’s conditions: the average across the month isn’t headline grabbing. But the pattern back-and-forth between weather types is remarkable. 

The year began warm, but within the first five days it had transitioned to a notably cold and dry period. But then, after a further couple of weeks, it transitioned again to a mild and wet spell.

Tapping into warmth

Sea-surface temperature anomalies from the latest OSTIA analysis, 01 February 2024, compared to the European Space Agency Sea Surface Temperature Climate Change Initiative (ESA SST CCI) climatology data. Indicative of the source region for southern UK coming from the maritime heatwave west of NW France and Portugal.

February may turn out to be remarkable on many fronts. Exceptionally mild and wet across a broad swathe of the UK in the first week, with a major change from the end of this week and beyond as very cold air from Scandinavia floods south into the UK.

We can project these extremes onto large-scale weather patterns: with high pressure towards Greenland; low pressure over Scandinavia; and low pressure occasionally stretching across the UK and into continental Europe. This pattern is characteristically described as a block; when the atmosphere gets ‘stuck’ for long periods of time.

Paul Davies is the Met Office’s Principal Meteorologist. He said: “Against this backdrop, the tropical Atlantic is very warm. Sea temperatures off the north-west African coast are currently comparable to values more typical for July.

Winds will continue to tap into this area of warmth, briefly drawing modified air north into southern and western parts of UK. This tropical-sourced air is being forced to rise as it comes up against the blocked pattern and over western hills bringing persistent, locally heavy rain here, and as the air descends to the lee side of these hills it has been introducing very mild and gusty conditions; because of the foehn effect.” This effect – which occurs where air crossing mountains is warmer and drier on the lee side – was also responsible for the record-breaking January temperature in NW Scotland. The weather station at Achfary recorded 19.9°C on 28 January: a new UK daily maximum temperature for January; and a new winter record for Scotland.

Colder conditions ahead

Paul Davies continued: “Then comes the expected change in weather, with winds switching north and drawing very cold air from the Arctic, initially arriving across Scotland, Northern Ireland and Northern England later this week and then heading further south into southern England. This may mean a significant contrast between the recent weekend, and next weekend with spring-like conditions one weekend and the potential for wintry hazards, especially in those regions susceptible to east and northeasterly winds across northern parts of the UK next weekend.”

Temperature anomalies from the latest GloSea forecasts for the week commencing 12 February. It shows cold air over the UK and deep cold residing over Scandinavia. GloSea is the seasonal prediction system developed and run operationally at the Met Office.

The forecasters’ challenges will be to determine:

  • the exact arrival time of the cold conditions;
  • and the associated battleground between the cold air in the north, and the mild in the south. This will create a zone of disruptive weather, including heavy rain, snow and ice.

At this stage it’s too early to predict with any confidence the evolving story. But if the boundary pivots and stalls, it could result in snow and blizzards for some. If the cold air digs south more quickly, frost and ice may be the hazards to watch out for; while if the cold air is restricted to the north, the hazards may be rain and strong winds in the south, with snow confined to Scotland, Northern Ireland and Northern England.

Phil Stocker is the chief executive of the National Sheep Association. He said: “The late winter and early spring period can be an extremely concerning time for livestock farmers, particularly those working in the UK’s more exposed and upland areas. Any cold snap, especially if accompanied by significant snowfall, can bring notable hardship to livestock, and of course hill farmers. 

“I find it helpful that the Met office is doing more to warn of the risk of bad weather conditions – it gives farmers the chance to assess the risks and do what they can to prepare.”

Paul Davies added: “It’s a close call with only minor wobbles in the weather patterns changing the course of the evolution and associated impact to the UK.”

Through to early March, there is increasing chance of sleet or snow, especially in the north and east of the UK with greater than normal potential for disruptive snow. The specific locations wintry hazards will become clearer as the lead time decreases.

Our advice therefore is to keep abreast with the latest forecasts and warnings. 

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A month of contrasts for January’s weather

Posted on 1 February, 2024 by Met Office Press Office

January 2024 brought a month of contrasts to the UK weather, with three named storms, a significant spell of cold, wintry weather and finally a new UK daily maximum temperature record for January.

Temperatures and rainfall amounts have varied throughout the month, with mild and wet weather interrupted by a cold and dry spell from the second week of January, albeit with some significant snow for northern areas of the UK.

The graph show January 2024 mean temperature and rainfall compared to average. The graph shows a cold and dry spell in the middle of the month, with mild and wet weather either side.

Overall, this means that the average mean temperature for the UK for January 2024 is near average according to provisional Met Office figures. UK mean temperatures ended the month at 3.8°C, around 0.1°C lower than the long-term average for the month.

The image shows a map of the UK's January 2024 mean temperature, compared to a 30-year average (1991-2020). It shows that the majority of the country experienced average temperatures across the month, but a large part of Scotland, plus small parts of southwest England and Northern Ireland, also experienced an average temperature lower than the 30 year average.

The fluctuations in rainfall throughout the month also resulted in near-average rainfall amounts for the month, though Northern Ireland and Scotland were drier than average. UK rainfall was 3% less than average, with 117.5mm of rain. Northern England saw 22% more rain than average, with 111.9mm falling in the month.

The image shows a map of the UK's January 2024 mean rainfall, compared to a 30-year average (1991-2020). It shows that the majority of the country experienced average rainfall across the month, but some areas of Wales, Scotland and the north of England, experienced more than the average amount of rainfall for the year.

Met Office Senior Scientist Mike Kendon said: “Overall, the UK temperature and rainfall for January were fairly near average but these belie the fact that the weather has never been too far away from the headlines. Storms Henk, Jocelyn and Isha all brought significant impacts, as did the cold and snowy conditions around the middle of the month.

“Of course, contrasting winter weather in the UK isn’t a new phenomenon, as subtle shifts in the jet stream can lead to significantly different conditions in the UK. This month we’ve seen clearly how cold northerly winds can bring winter hazards, while Atlantic westerlies can bring some impactful storms. When you add in a late-month warm spell from the south, you get a sense of the mixed conditions the country has had. What this January clearly demonstrates is just how abrupt these changes in weather type can be.”

Gardeners will be glad of more subdued rainfall figures compared to the wet conditions of December, according to Royal Horticultural Society Chief Horticulturist Guy Barter. He said: “Gardeners will have been grateful for a break in January from the rainy autumn and winter weather that has hindered getting the garden ready for spring.

“Although conditions have been pleasant, a cold, but not bitter, January is favoured by gardeners as it holds back the spring flowering of fruit trees and bushes that are vulnerable to frost damage if they flower too early. Gardeners will be hoping for a dry, chilly February.”

Contrasting temperatures

A northerly flow of air resulted in a period of significant cold weather from around the second week of January, with snow and ice hazards for many in the northern half of the UK, especially the north of Scotland. Shetland was particularly hard-hit with bitter northerly winds and temperatures struggling to rise much above freezing with deep lying snow.

On 17 January, -14°C at Dalwhinnie (Invernesshire) was the lowest temperatures dipped in the month, with a snow depth of 37cm reported at Altnaharra (Sutherland) on 18 January. Despite the UK’s warming climate, spells of wintry weather are to be expected and this was one of the more notable such spells since the exceptional December of 2010.

On the flip side, the month started mild and very wet and has concluded mild, with a new UK daily maximum temperature record for January of 19.9°C recorded at Achfary on 28 January. This is also Scotland’s highest winter temperature on record.

Mike Kendon explained some of the meteorological factors behind north-west Scotland’s unusually high temperatures near the end of the month. He said: “The Foehn effect causes a marked contrast in temperature across a mountainous area, with cooler, moister conditions on the windward side and warmer, drier conditions on the leeward side as the air dries out as it is forced up and over the higher ground.

“This effect can be responsible for some unusually high winter temperatures in both Scotland and Northern Ireland, although these tend to be highly localized. While the Foehn effect was the primary cause of this record, we must set this against a backdrop of increasing mean and maximum temperatures more generally as our climate continues to warm.”

Since 2011, the UK has recorded a new individual highest maximum daily temperature extreme for six of the 12 months of the year – January (2024), February (2019), July (2022), October (2011), November (2015) and December (2019). In contrast, none of the UK’s individual lowest minimum temperature extremes in a month have occurred this century.

The below maps show contrasting temperature anomalies seen in the month, with a cold pool of air on 17 January and a warm southerly flow coupled with the Foehn effect in parts of Scotland on 28 January.

The image shows two maps illustrating contrasting temperature anomalies seen in the UK in January 2024 compared to a 30-year average (1991-2020). The map on the left is all blue and the map on the right is almost all red. The left map was from 17 January, where the mean temperatures are very low because of a cold pool of air. The map on the right is from 28 January, where a warm southerly flow coupled with the Foehn effect in parts of Scotland brought very warm temperatures for this time of year.

A sunny start to the year

Despite the mix in conditions, sunshine was a relatively frequent visitor in January.

The UK had its sixth sunniest January on record in a series which goes back to 1910. There were 61 hours of sunshine on average in the UK, which is 28% more than average. The relatively sunny month was a welcome contrast to December, with just 27.9 hours, around two-thirds of normal and less than an hour a day.

Sunshine map : The image shows a map of the UK's January 2024 average sunshine duration, compared to a 30-year average (1991-2020). It shows that the majority of the country experienced higher than average hours of sunshine, with parts of southern Scotland and the Northern Isles experiencing much more sunshine than the 30-year average.

January’s sunny theme was replicated across much of the UK, with England and Scotland recording sunshine amounts within their top ten sunniest for the month, with Wales and Northern Ireland also seeing sunshine amounts well above average.  

Three storms in the month

Three named storms impacted the UK in the month as Henk, Isha and Jocelyn brought strong winds and heavy rain for some. A recent blog looks at the underlying factors behind what has been a stormy autumn and winter so far.

Henk brought significant flooding impacts as well as strong winds, while Isha was the most notable windstorm since Eunice in 2022, with extensive Amber wind warnings issued by the Met Office as well as an unusual overnight red warning for some. A gust of 99mph was recorded in Northumberland as part of Storm Isha.

Storm Jocelyn, which was named by Met Eireann, continued to bring strong winds to much of the north of the UK.

Provisional January 2024Mean temp (°C) Sunshine (hours) Rainfall (mm) 
 Actual Diff from avg (°C)Actual% of avgActual% of avg
UK 3.8-0.1  61.0128  117.597
England 4.40.0  70.6128 85.1102
Wales 4.4-0.0  56.6120 161.9104
Scotland 2.5-0.5  46.8133 165.193
N Ireland 4.2-0.3  55.6130 86.075

Winter so far

Meteorological winter so far is tracking wetter and slightly warmer than average, though with a month still to go there is time for these figures to change significantly.

At this point in the season you’d expect to have seen 68% of the season’s total seasonal average rainfall. At the conclusion of January, the UK has so far seen 89% of the average rainfall for the whole of the season, although much of north-east England and eastern Scotland have already received more than the whole-season average rainfall, with a month still to go.

The image shows a map of the UK's 2024 winter rainfall so far (from 01 December to 31 January.) The map shows it as a % of the winter averages from 1991-2020. It is important to note that the totals are compared with the average of the WHOLE season, and what the map shows is just 01 December to 31 January 2024. We would normally expect around 68% of the total average at this point in the season, however the map shows in some areas, more than 150% of the seasonal rainfall average has already been reached.
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Solar maximum in sight – but when will it be?  

Posted on 30 January, 2024 by Met Office Press Office

Throughout autumn and winter there have been a number of sightings of the Northern Lights, or the aurora borealis, in the UK. As 2024 continues, the question for many space weather experts is when we’ll see a peak in the Sun’s activity as part of this solar cycle.  

The auroras on Earth, which are most commonly seen over high polar latitudes but can often spread south to be visible over parts of the UK, are chiefly influenced by geomagnetic storms which originate from activity on the Sun.  

Space weather forecasters, like those who work at the Met Office Space Weather Operations Centre (MOSWOC), spend their time studying the Sun’s activity and forecasting the arrival of coronal mass ejections which cause geomagnetic storms, solar flares and solar radiation storms, collectively known as space weather. Space weather typically originates from sunspots on the Sun’s surface.  

Image: Richard Ellis, Royal Photographic Society

While these events contribute to the magnificent displays of colours in the sky as part of the auroras, the most severe of these events also have the potential to cause radio blackouts, disrupt GPS systems and interact with some ground-based infrastructure on Earth.  

Forecasting of specific events is incredibly complex, with satellites looking at features on the Sun including sunspot activity on the Sun’s surface from around 93million miles away. However, the Sun has a natural rhythm, called the solar cycle, which drives varying levels of activity, with the next peak due in 2024. This cycle works on around an 11-year cycle from one solar maximum to the next maximum.  

Met Office Space Weather Manager Simon Machin explained: “While the solar cycle doesn’t help determine specific space weather events, what it does is help our forecasters understand the context of their forecasts.  

“In its simplest terms, the solar cycle is linked to the number and intensity of sunspots that are visible on the surface of the Sun. This affects the likelihood of space weather events impacting the Earth.” 

When will the solar maximum be? 

The last solar minimum, when the Sun’s activity was at its lowest in the cycle, occurred in December 2019, with the Space Weather Predictions Center (SWPC) now predicting that the solar maximum will occur in 2024.  

However, as Simon explains, the passing of solar maximum doesn’t mean that further space weather events won’t occur.  

“One of the curious things about the solar maximum is that it’s not possible to declare it has occurred until after it has happened and when you observe that reduction in sunspot activity,” said Simon.  

“We know that the solar maximum increases the chances of space weather events impacting the Earth, but even as you move away from it as get through 2024 into 2025 and beyond, the Sun will continue to emit solar flares and geomagnetic storms. This means that further auroral displays are likely, as well as an ongoing chance of potentially impactful space weather events, even as we move towards the next solar minimum.”  

MOSWOC is one of a handful of 24/7 space weather prediction centres around the world, constantly looking for signs that the Sun’s activity could impact the Earth. By providing warning of these events reaching the Earth, mitigations can be taken by key industries to avoid some of the most severe impacts from extreme space weather events.

Find out more about the Met Office Space Weather Operations Centre or view the latest Met Office Space Weather forecast.

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Is the UK winter going as forecast?

Posted on 29 January, 2024 by Met Office Press Office

There has been much coverage of the weather in recent weeks with what has so far felt like an unusually stormy autumn and winter, followed by a spell of extremely cold weather with impacts from snow and ice for many, and then on Sunday (28/01/24) a new provisional maximum temperature record for the UK for January was recorded in northwest Scotland.   

To understand what has been happening over the last few months and what we might expect for the coming months, we need to look at the weather outside the UK. Global weather is interconnected and large-scale global weather and climate systems, known as climate drivers, can have major impacts on the UK at this time of year. So, what are these drivers and what are they doing at the moment? 

Climate Drivers 

El Niño, the naturally occurring warming of the Pacific Ocean, releases heat into the atmosphere, creating warmer and wetter air which can trigger extreme weather around the globe, resulting in impacts such as the ongoing drought in the Amazon.  

As we are all aware, so far this winter, the UK, has had a wet and stormy December followed by a colder spell in January. This type of weather is consistent with what we would expect during an El Niño winter. Although we are now in a milder interlude with westerly and southerly winds, the long-range outlook still contains a good chance of a return to colder conditions. 

Earlier this month the Met Office announced that globally, 2023 was the warmest year on record (data back to 1850), and it was the tenth successive year that has equalled or exceeded 1.0 °C above the pre-industrial period (1850-1900). Professor Adam Scaife, Principal Fellow and Head of Monthly to Decadal Prediction at the Met Office, said: “The above average temperatures have been driven largely by climate change but are topped up by El Niño. During an El Niño event, winds in the eastern Pacific weaken, keeping warm waters closer to the surface releasing more heat into the atmosphere and raising global temperature.  

“The ongoing Amazon drought and wet conditions in parts of Northern Europe in December are also consistent with El Niño.” 

Although El Niño has likely peaked in the tropics, its impacts are still being felt around the globe and Professor Adam Scaife, added: “The phenomenon could well lead to unprecedented global temperatures this year, with 2024 being the hottest year on record globally, potentially pushing the world temporarily past the key 1.5C warming milestone.” 

El Niño is not the only factor driving our weather patterns. Other drivers influencing the UK this winter include the Quasi-Biennial Oscillation (QBO). This is a regular variation of the winds that blow high above the equator. The QBO is currently in an easterly phase, increasing the chance of cold northerly or easterly winds from the Arctic and continental Europe. The Stratospheric Polar Vortex, has tended to be weaker than normal so far this winter but its strength has now returned to around average, and its influence is likely to be limited in the immediate future. An active Madden-Julian Oscillation favours westerly winds over the UK during early February but then a reduction in westerly winds during mid and late February. 

All these effects are happening on a background of warming UK winters, consistent with wider global warming trends.  

Taking the ‘global drivers’ into consideration, our long-range forecast systems suggest February will start off mild, with the chance of cold weather increasing as we go through the month and into March. This means we could yet see some cold weather-related impacts such as snow and ice. This increased chance of cold does not exclude the possibility of milder conditions.  

Despite any speculation you may read elsewhere, the science simply does not allow for specific detail on the amount of rain or snow over the coming months or exactly when severe weather may occur. However, long-range forecasts can provide useful information on the likelihood of possible conditions averaged over the whole of the UK.  

The science of longer-range and seasonal outlooks is at the cutting edge of meteorology and the Met Office is one of the leaders in scientific research in the area. Even with ‘perfect’ prediction systems, the fundamentally chaotic nature of the atmosphere means these predictions will always be concerned with the likelihood of different kinds of possible weather conditions and the levels of risk of impacts they might bring.  Even with ‘perfect’ prediction systems, the fundamentally chaotic nature of the atmosphere means these predictions will always be concerned with the likelihood of different kinds of possible weather conditions and the levels of risk of impacts they might bring.   

You can check the long range forecast and daily weather forecast on our website. You can also follow us on Twitter and Facebook, as well as on our mobile app which is available for iPhone from the App store and for Android from the Google Play store. Our three-month outlooks are updated each month. Keep track of current weather warnings on the weather warning page.  

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