1st half of month: rather dry, settled with above average sunshine. After a chilly start, turning much milder in the first 7 days. Turning colder from around the 11th, with high pressure to the north and low pressure over southern Europe pulling in chilly north or northeasterly winds through to the weekend of 15th-16th. Showers likely in the north and east, perhaps wintry in nature.
2nd half of month: after a dry first few days, high pressure will retreat east, allowing low pressure to move in close to the west, bringing milder and increasingly unsettled conditions to most parts through to the weekend of 22/23rd. Thereafter, some uncertainty, but a return to generally more settled conditions is favoured, as high pressure re-establishes close-by.
Probability for temperatures against 1991-2020 average: 50% chance of above average, 30% chance of average or 20% chance of below average.
Probabilities for rainfall: 60% of chance for below average, 20% chance of average, 20% chance of above average.
High latitude blocking may develop in early April, due to the drip down effects of the early March final stratospheric warming, forcing a more southerly low-pressure track than average over the Atlantic with lower pressure over mainland Europe and high pressure to the north or northeast. This increases the chances of colder-than-average and showery conditions during the start of the month, more especially in the south and west. Perhaps drier in the north. Then perhaps turning more unsettled and milder across all parts towards mid-month. Temperatures a little below average before recovering into the second week.
As we enter the second half of the month, low pressure may establish close to the west or southwest, bringing unsettled and milder conditions, with spells of rain and showers across all parts through to later in the month. Possibly a drier and warmer towards the end of the month, but low confidence. Temperatures more likely to be above average in the second half than first half.
Probability for temperatures against 1991-2020 average: 40% chance of average, 30% chance of below average or 30% chance of above average.
Probabilities for rainfall: 40% of chance for average, 30% chance of below average, 30% chance of above average.
Low confidence, but we think low pressure most likely to be positioned to the west or southwest with high pressure close to the north and east of the UK for larger parts of the month than not.
Overall, it's looking like a warmer-than-average month, with the flow more likely from southeast, south or southwest for most of the time. Potential for one or two dry and very warm spells, but risk showers or longer spells of rain at times - especially in the west or southwest. Rainfall likely to be below average overall, wettest in the west and southwest, drier in the north and east. The start of the month most likely to be drier than later in month.
Probability for temperatures against 1991-2020 average: 50% chance of above average, 30% chance of average or 20% chance of below average.
Probabilities for rainfall: 50% of chance for below average, 30% chance of average, 20% chance of above average.
Continue below for the in depth forecast and explanation of the factors which are expected to influence the weather this Spring.
A major Sudden Stratospheric Warming (SSW) occurred at 10hPa 60N on March 9th. This could be a Stratospheric Final Warming (SFW) - if the winds at this height of the polar stratosphere do not turn westerly within 10 days, latest 00z GEFS mean and EPS mean (below) seem to back this idea The major warming is from wave no 1 over Alaska / eastern Siberia towards the north pole - causing a displacement of the Stratospheric Polar Vortex towards NE Europe before then, though the reversal not translating down to the troposphere until perhaps late this month or early April.
Generally, a Stratospheric Final Warming (SFW) occurs early when the planetary wave activity is relatively strong in the Northern Hemisphere, mainly during the middle and late March; however, when solar heating acts as the main factor, a SFW may not occur until early May.
A SFW exerts a significant impact on the tropospheric - where weather and climate occurs, in early spring its impacts can be similar to the SSW event in winter, as in that it can induce a negative phase of the North Atlantic Oscillation (NAO) in spring - with high latitude blocking and risk of colder weather.
The earliest SFW recorded was on 5th March 2016, that was driven by wave 1, with other early ones caused by wave 1: 13 March 2005; 22 March 1992; 19 March 1986; 12 March 1978; 17 March 1975. The composite 500mb pattern for March and April looks like this:
However, there is a great deal of uncertainty over whether the reversal of winds in the stratosphere, typical of a SSW or FSW event, propagate down to the troposphere - where our weather happens. Should the reversal move down, it could allow pressure / heights to rise in the higher latitudes beyond March 20th.
Current stratospheric wind forecast suggest the reversal could be very slow to propagate down to the troposphere, if at all, with early April more likely to see any impacts which could manifest as high latitude blocking and upper troughs further south. If this occurs, should the pressure patterns be in the right place, then colder conditions are possible for the UK in early April. However, not all SSWs lead to cold spells in winter or spring, sometimes they can lead to mild or even warm conditions (in spring), depending on where the ridges or troughs position when the changes occur. Sometimes a SSW reversal doesn't propagate down to the troposphere, so there's no effect and other drivers control the weather patterns.
Around two out of three major Sudden Stratospheric Warmings / Final Warmings lead to a Negative North Atlantic Oscillation (-NAO) which is often associated with blocking high pressure at higher latitudes of Greenland and/or Scandinavia - which forces the Atlantic storm track further south and also causes cold air to push south into Europe, including the UK. The NAO is closely related to the Arctic Oscillation, so when the NAO goes negative, the AO goes negative too, pushing cold arctic air south to lower-latitudes.
It usually takes a week or two for the reversal to propagate from the stratosphere to the troposphere, so effects may not occur until early April. Sometimes it can be a more rapid response in the troposphere. Even it does happen and initiates high latitude blocking, there is no guarantee that cold air will reach the UK, as areas of low pressure and high pressure need to align in a particular way for this to occur.
Some longer range output, EC46 for example, has been pointing to high latitude blocking with positive height anomalies to the north from Scandinavia to Greenland in late March and early April.
Given this and the greater probability that a SSW may lead to high latitude blocking and a risk of cold weather, the spring forecast has factored in greater potential for below average temperatures in early April before temperatures recover from mid-month.
Teleconnections are a recurring and persistent, large-scale pattern of pressure and circulation anomalies that spans vast geographical areas. Although these patterns typically last for several weeks to several months - such as the Arctic and North Atlantic Oscillations (AO / NAO), they can sometimes be prominent for several consecutive years, such as ENSO (El Nino or La Nina) thus reflecting an important part of both the interannual and interdecadal variability of the atmospheric circulation. Many of the teleconnection patterns are also planetary-scale in nature and span entire ocean basins and continents - such as ENSO. For example, some patterns span the entire North Pacific basin, while others, such as the NAO, extend from eastern North America to central Europe.
NAO currently negative but forecast to turn positive in a week's time
The ENSO will be discussed further on, but here we will look at the NAO forecasts - which as index of pressure patterns that most directly influence UK weather throughout the year. Teleconnection patterns linked to phases of the North Atlantic Oscillation (NAO) reflect large-scale changes in the atmospheric wave and jet stream patterns, and influence temperature, rainfall, storm tracks, and jet stream location/ intensity over vast areas. Thus, they are often the culprit responsible for abnormal weather patterns occurring simultaneously over seemingly vast distances. For example, the 1995/86 winter was very cold and snowy over much of eastern North America, while northern Europe and Scandinavia were cold and southern Europe/ northern Africa experienced very wet and stormy conditions. These conditions were all partly related to the same teleconnection pattern: a strong negative phase of the North Atlantic Oscillation (NAO).
The NAO has turned positive to negative during the first 10 days of March, reflective of the jet stream and Atlantic storm track shifting further south across southern Europe, with colder conditions for the UK towards mid-month. A return to more positive values during the second half of March looks more likely, bringing the Atlantic low track further north with milder and more unsettled conditions to the UK.
Beyond a month, confidence in teleconnections and related weather regimes becomes rather low.
Although the MJO is a wave of enhanced convection that circum-navigates the global tropics, it does impact the upper patterns at high latitudes of the northern hemisphere, so is a useful tool to use for predictions for 3-4 weeks ahead, but no more than that really.
The MJO, although occurring the tropics, has far-reaching impacts on northern hemisphere extratropical weather through Rossby Wave propagation. The Rossby Wave propagation depends on the longitude of where the enhanced convection associated with the MJO wave takes place. As the MJO has a significant impact on northern hemisphere weather patterns, including the North America, Atlantic and Europe, there are correlations that can be made between the 8 different phases of the MJO and the lagged impacts on the upper air patterns that might be expected over the North Atlantic and Europe based on composites of previous events. The impact of the MJO on North Atlantic and European weather patterns depends on the strength of amplitude of the wave.
The Madden Julian Oscillation (MJO) moved through phase 1 to 2 in the first week or so of March and then looks head through phase 3 towards mid-month. Lagged composites (around 10 days) in La Nina through phases 1 and 2 favour low pressure close to the west and southwest but low track shifting south with time and pressure rising to the north, reflecting a negative NAO signal and colder weather for the UK. Phase 3 lag indicates low pressure to the south and high pressure to the north, continuing the -NAO signal.
However, this is only one piece of the puzzle, with destructive or constructive interference possible from other teleconnections such as a strong polar vortex to start the month but its potential collapse with the SSW / FSW event earlier month.
There are no hard and fast rules over how ENSO impacts European weather patterns, whether it's in El Nino, neutral or La Nina. El Niño or La Nina primarily affects weather patterns in the tropics, but changes to the weather in these regions can have knock-on effects all over the world. Even thousands of kilometres away in northern Europe.
La Nina conditions are present. Equatorial sea surface temperatures (SSTs) are near-to-below average in the central and east-central Pacific Ocean. The NOAA expects La Nina conditions to persist in the near-term, with a transition to ENSO-neutral likely during March-May 2025 (66% chance).
However, sea temperatures are rising above average in the eastern tropical Pacific - which will continue to weaken the trade winds which could mean an abrupt end to La Nina, though perhaps not until late spring at the earliest.
For now, will factor in La Nina as one of the background drivers among other drivers such as the stratosphere - troposphere relationship and also other cycles such as MJO.
While the ENSO teleconnection towards the Pacific North American region is well-researched and understood, there are still many processes that blur the ENSO signature over the North Atlantic-European region.
The way ENSO is used in this forecast will be to draw weather pattern composites of previous spring months featuring a La Nina weakening to neutral in Spring.
Years since 1980 which saw weak La Nina conditions present in February before weakening to Neutral in Spring were: 1981, 1986, 1996, 2001, 2006, 2009, 2014, 2018. A composite reanalysis of those years for April and May at 500 hPa shows the following:
I will only use the composites for April and May, as the extended model forecasts of EC and CFS will have better skill, given they will be using current atmospheric states, factoring in La Nina forcing, the MJO and perhaps the SSW / FSW around mid-month. Over a month out and the analog composites, combined with seasonal forecast will be relied upon to make some assumptions on how patterns may play out.
Upper trough close to the west and southwest and ridging to north and east in April, upper trough close to the west and ridging to the east in May. This is quite different to the February seasonal outlook from the models - which indicate high pressure being dominant both months.
The March update to the C3S multi-model prediction forecasts for April and May for mean sea level pressure are below and suggests high pressure close by to the west for April, no strong signal for high or low pressure in May.
The March seasonal model output from ECMWF,indicates low pressure over the UK for April, which is quite a departure from the February update which had high pressure over UK. May shows high pressure to the west and northwest. An unsettled outlook for April, perhaps more settled for May.
These daily updated forecast go out to 42 days, so can give a broad idea of trends for up to a month ahead when used with EPS clusters too. The signal is for blocking to the north of the UK mid-month to the north to shift east from around the 17th, allowing low pressure to move in close to the west and eventually dominating the UK through rest of the month. However, a signal for northern blocking and low pressure to the south of the UK to return early April.
Also, the UK Met Office contingency forecast is out.
Met Office contingencies outlook
The World Meteorological Organization (WMO) has confirmed that 2024 is the warmest year on record, based on six international datasets. The past ten years have all been in the Top Ten, in an extraordinary streak of record-breaking temperatures. The statistics so far this year suggest January 2025 was the warmest January globally, with an average ERA5 surface air temperature of 13.23°C, 0.79°C above the 1991-2020 average for January. This despite an emerging La Nina, which typically has a cooling effect.
With all this record warmth in the atmosphere, the oceans are near record warm globally too, The average sea surface temperature (SST) for January 2025 over 60°S-60°N was 20.78°C, the second-highest value on record for the month, 0.19°C below the January 2024 record. Average temperatures across the world's oceans reached an all-time high in 2024, a study showed. The temperatures surpassed even those of 2023, which themselves represented a marked uptick over any previous years on record.
The weather is becoming more affected by warming oceans because the warmer waters add heat and moisture to the atmosphere - making our weather more unpredictable. So making 3 month seasonal forecast is becoming more challenging with the added unpredictability.
Stay upto date with the long range forecast throughout the year with the Month Ahead Forecast - Updated Every Monday.
