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The common UK winter has turn into round 1C hotter and 15% wetter over the previous century, new Carbon Transient evaluation reveals.
The evaluation covers greater than 100 years of information on temperature, rainfall, wind velocity and snow, to evaluate how UK winters have modified.
The info present that extraordinarily heat and moist winters have gotten extra widespread. Six of the ten warmest winters on document have been within the twenty first century, and 4 of those additionally rank within the prime 10 wettest years on document.
Regardless of the pattern in direction of milder situations, excessive chilly snaps nonetheless hit the UK. The winter of 2009-10, for instance, was dubbed the “Huge Freeze of 2010” and clocked in because the UK’s least-windy, second-snowiest and eighth-coldest winter on document.
Nevertheless, excessive chilly intervals have gotten much less widespread. On common, the UK noticed greater than 12 snow days every winter in 1971-2000. This dropped to 9.5 snow days every winter by 1991-2020.
Because the local weather continues to heat, the UK can count on winters to proceed getting hotter and wetter. Met Workplace projections counsel that, underneath an emissions pathway consistent with present world insurance policies, the typical UK winter by 2080-99 can be 2C hotter and 11% wetter than they have been in 1981-2000.
Hotter winters
The UK Met Workplace has been accumulating meteorological information from hundreds of climate stations throughout the UK for the reason that Eighties. Utilizing this information, it has produced a gridded dataset referred to as HadUK, which offers full protection throughout the UK for a variety of local weather variables – together with rainfall, temperature, snow days and wind velocity – on a one-square-kilometre grid.
Carbon Transient has analysed the information for meteorological winters – outlined as December, January and February – to find out how climate situations have modified since information started.
The plot beneath reveals a timeseries of annual winter common temperature (darkish blue) over 1884-2021. These are proven as anomalies – that’s, the distinction in comparison with a baseline, which on this case is the typical winter temperature over 1991-2020.
(Winters are proven on graphs on this article in line with the yr through which December falls. For instance, the winter of December 2021 to February 2022 is proven as 2021.)
The Met Workplace, consistent with the World Meteorological Organisation, makes use of 30-year averages to evaluate adjustments in UK local weather. The desk beneath reveals common absolute UK winter temperatures for overlapping 30-year time intervals throughout the total information document.
Time periodAverage temperatureMaximum temperatureMinimum temperature
1881-19102.96*5.77*0.18*
1891-19203.296.060.53
1901-19303.506.210.80
1911-19403.516.210.83
1921-19503.416.120.73
1931-19603.296.050.56
1941-19703.095.840.35
1951-19803.175.910.46
1961-19903.225.940.51
1971-20003.656.400.91
1981-20103.756.580.94
1991-20204.126.971.28
Common, most and minimal winter temperatures for overlapping 30-year time intervals, from 1881 to 2020, utilizing the December-February common of imply month-to-month temperatures. An asterisk (*) signifies {that a} full 30 years was not obtainable for this common.
The common UK winter in 1991-2020 was 0.9C hotter than throughout 1961-90. The latest 30-year interval additionally contains the warmest most, minimal and common temperatures since Met Workplace information started.
As well as, with a mean winter temperature of 4.64C, the most-recent decade (2013-22) – not proven within the desk – has seen an extra temperature improve of 0.52C above the 1991-2020 common.
Hotter winters are already impacting UK wildlife. For instance, Grahame Madge – senior press officer for the Met Workplace – informed the Guardian that animals together with hedgehogs, bats and butterflies are rising from hibernation too early:
“Irregular heat spells throughout winter can encourage species out of hibernation. Butterflies reminiscent of crimson admirals and small tortoiseshells and different bugs could be significantly challenged as they’ll emerge largely with out entry to life-saving meals sources like nectar. If the nice and cozy spell is adopted by a return to colder situations, the hibernating people can have used up invaluable power reserves with out with the ability to exchange them, probably with disastrous penalties.”
In the meantime, the Nationwide Belief says hotter winters have “significantly devastating impacts for timber”, as chilly snaps are sometimes not lengthy sufficient to kill off dangerous ailments and pests.
particular person years offers a extra detailed image. The graphic beneath reveals the warmest and coldest 10 winters within the UK since 1884. The darkish blue line reveals common UK winter temperature, and crimson and blue dots point out the warmest and coldest particular person winters, respectively. The desk beneath reveals the dates and temperatures of those winters.
Warmest wintersColdest winters
YearsTemperature (C)Years Temperature (C)
11988-995.761962-63-0.31
22006-075.531894-950.42
32015-165.431946-470.75
41997-985.401978-791.13
52019-205.281939-41.23
61974-755.221916-171.33
72021-225.201928-291.46
82013-145.192009-101.63
91934-355.131885-81.65
102018-195.091940-411.80
Warmest and coldest 10 winters within the UK since 1884. The darkish blue line reveals common UK winter temperature, and crimson and blue dots point out the warmest and coldest particular person winters. The desk beneath reveals the dates and temperatures of those winters. Credit score: Chart by Carbon Transient, primarily based on the Met Workplace HadUK dataset.
The graph reveals that six of the ten warmest winters on document have occurred within the twenty first century. Conversely, solely one of many UK’s coldest 10 winters have been within the twenty first century – the winter of 2009-10.
The Met Workplace additionally offers country-level information for various components of the UK. The plot beneath reveals 10-year rolling common winter temperature for England (darkish blue), Scotland (crimson), Northern Eire (gentle blue) and Wales (yellow).
The plot reveals that Scotland constantly sees the coldest winters, whereas England, Wales and Northern Eire expertise winter temperatures which might be a mean of round 1.5-2C hotter.
Snow days
As common temperatures rise throughout the UK, extraordinarily chilly days have gotten much less widespread, whereas record-breaking heat days have gotten extra frequent.
5 of the highest 10 warmest days ever recorded throughout UK winters occurred throughout a single week February 2019.
Carbon Transient analysed the warmest most and coldest minimal temperature on document for every UK winter. The desk beneath reveals the years with the warmest (crimson) most day by day temperatures and coldest (blue) minimal day by day temperatures since 1960.
Warmest most temperaturesColdest minimal temperatures
Temperature (C)YearTemperature (C)Yr
116.12018-19-10.21986-87
214.31997-98-10.11962-63
314.02015-16-10.01981-82
413.81989-90-9.91978-79
513.62003-04-9.51971-72
613.51985-86-9.32010-11
713.42011-12-9.11995-96
813.32016-17-8.91969-70
913.32021-22-8.72009-10
1013.21994-95-8.71968-69
Years with the ten warmest (crimson) most temperatures, and coldest (blue) minimal temperatures, primarily based on particular person winter days since 1960. Credit score: Chart by Carbon Transient, primarily based on the Met Workplace HadUK dataset.
Many of the warmest winter extremes on document have been within the twenty first century. In the meantime, a lot of the coldest extremes have been within the twentieth century.
A method of measuring the change in excessive chilly days is to depend the variety of “frost days” – days with a minimal temperature beneath 0C – recorded all through the winter. One other manner is to depend the variety of “snow days”, when snow could be seen on the bottom at 9am.
Dr Mark McCarthy is the top of the Met Workplace Nationwide Local weather Info Centre, which manages the UK’s local weather information. He explains that to calculate snow days, a person appears to be like at a “consultant patch of floor” at 9am within the morning, and if no less than half of it’s lined in snow, then it’s counted as “snowy”.
These outcomes are averaged throughout lots of or hundreds of observations. Which means that, for instance, “a mean of 5 days of snow may imply that half of that area had 10 days and half the area had no days”, he explains.
The plot beneath reveals the variety of frost days since 1960 (crimson) and snow days since 1971 (blue) over winter. The black strains present the 10-year operating common.
The desk beneath reveals the full variety of first and snow days throughout UK winters for 4 overlapping 30-year time intervals.
Time periodFrost daysSnow days
1961-199038.43–
1971-200035.0712.29
1981-201035.1711.73
1991-202032.759.54
Complete variety of frost and snow days for 30-year time intervals, from 1931 to 2020, utilizing the December-February common of imply month-to-month temperatures. An asterisk (*) signifies {that a} full 30 years was not obtainable for this common.
The plot reveals that air frost and snow days are carefully linked. Snow will typically not kind if the bottom temperature is above 5C, and within the UK, the heaviest snowfalls are inclined to happen when the air temperature is between 0C and 2C.
On common, the UK noticed 12.3 snow days every winter over 1971-2000. This dropped to 9.5 snow days every winter by 1991-2020.
There’s additionally regional variation in snow days. Over your entire 1971-2020 dataset, Scotland obtained 18.6 days of snow per winter on common, whereas the UK, Northern Eire and Wales obtained between 7.2 and eight.8.
“Important and widespread mendacity snow might need been thought of pretty typical for a UK winter of a number of a long time in the past,” says the Met Workplace’s newest State of the UK local weather report. Nevertheless, it provides that “the sort of occasion has turn into more and more uncommon in a warming local weather during the last two or three a long time”.
The graph beneath reveals the UK winters with the best (gentle blue dots) and smallest (crimson dots) variety of snow days since 1971.
Snowiest wintersLeast snowy winters
YearsSnow daysYearsSnow days
11978-7935.622019-202.12
22009-1030.591991-922.39
31981-8226.902007-082.97
41985-8623.691988-893.15
52010-1123.132021-223.35
61984-8521.541997-983.45
71976-7720.772013-143.49
81977-7818.542016-173.57
91995-9618.432005-063.72
101990-9118.131974-753.90
Snowiest and least snowy 10 winters within the UK since 1884. The darkish blue line reveals seasonal “snow days”, and crimson and blue dots point out the snowiest and least snowy particular person winters. The desk beneath reveals the dates and variety of snow days of those winters. Credit score: Chart by Carbon Transient, primarily based on the Met Workplace HadUK dataset.
Whereas the local weather is changing into milder and snow is changing into much less widespread, very chilly and snowy winters can nonetheless occur. For instance, the winter of 2009-10, dubbed the “Huge Freeze of 2010” in components of the UK media, was the least-windy, second-snowiest and eighth-coldest winter on document within the UK.
Extreme snowfall that winter brought about “very vital disruption throughout the UK”, in line with the UK Met Workplace, which provides that “transport was significantly badly affected with snowfalls inflicting quite a few highway closures, and practice and flight cancellations”.
On 18 December 2009, 5 Eurostar trains obtained caught within the Channel Tunnel after chilly temperatures brought about electrical failures, trapping 2,000 folks for 16 hours. All Eurostar companies have been cancelled for the subsequent three days.
In January that winter, BBC Information reported that “heavy snow and freezing temperatures has brought about chaos throughout Scotland over the previous three weeks, with lots of of faculties closed and motorists dealing with hazardous situations on the roads”.
Analysis from the UK Met Workplace signifies that the percentages of the UK having a winter as chilly because the one in 2009-10 will drop to lower than 1% by the tip of the century as world temperatures proceed to rise.
Wetter winters
The whole quantity of rainfall recorded throughout UK winters can be rising. The plot beneath reveals whole winter rainfall in mm over 1836-2021 (blue) and the 10-year rolling common (black).
The desk beneath reveals common UK winter rainfall totals for a collection of overlapping 30-year time intervals throughout the total information document.
30-year periodAverage annual winter rainfall (mm)
1831-1860254.69*
1841-1870276.00
1851-1880284.28
1861-1890287.46
1871-1900281.51
1881-1910279.06
1891-1920300.55
1901-1930311.07
1911-1940314.51
1921-1950305.00
1931-1960298.76
1941-1970290.82
1951-1980293.23
1961-1990301.82
1971-2000329.22
1981-2010330.01
1991-2020346.98
Common winter rainfall over overlapping 30-year time intervals, from 1831 to 2020, utilizing the December-February common of imply month-to-month temperatures. An asterisk (*) signifies {that a} full 30 years was not obtainable.
Between 1961-90 and 1990-2020, the UK winters grew to become 15% wetter on common – growing from round 300mm of rainfall to virtually 350mm. The more moderen decade of 2012-21 – not proven within the desk – has seen additional will increase, with common winter rainfall of 380mm.
The Met Workplace additionally offers country-level rainfall information. The plot beneath reveals 10-year rolling common winter temperature for England (darkish blue), Scotland (crimson), Northern Eire (gentle blue) and Wales (yellow).
The graph reveals that rainfall is growing throughout all 4 areas of the UK, however stays constantly the bottom in England and the best in Scotland and Wales.
Wanting on the wettest and driest years throughout the UK reveals that particular person rainfall extremes have gotten extra widespread. In a rating going again to 1884, seven of the driest years have been within the nineteenth century, whereas three have been within the twentieth. Not one of the driest years on document have been within the twenty first century.
In the meantime, 4 of the rainiest winters have been within the twenty first century. The graph beneath reveals the wettest (blue dots) and driest (crimson dots) winters since 1884.
Rainiest winters (mm)Least wet winters (mm)
YearsWinter rainfallYearsWinter rainfall
12013-14540.31963-64121.3
22015-16505.71890-91141.4
31994-95498.21844-45164.6
41989-90482.21933-34170.4
52019-20474.51846-47171.3
61876-77458.01962-63171.5
71914-15450.71857-58176.6
81868-69439.61840-41179.6
92006-07435.81937-38186.9
101993-94431.41854-55189.1
Wettest and driest 10 winters within the UK since 1884. The darkish blue line reveals whole winter rainfall, and blue and crimson dots point out the driest and wettest snowy particular person winters. The gray dashed strains the amount of rainfall recorded in the course of the rainiest and least wet winters on document. The desk beneath reveals the dates and whole rainfall in mm of those winters. Credit score: Chart by Carbon Transient, primarily based on the Met Workplace HadUK dataset.
The truth that UK winters are getting wetter is smart, McCarthy tells Carbon Transient, as a result of because the ambiance heats up, it is ready to maintain extra moisture, which may then fall as rain. In keeping with the Clausius-Clapeyron equation, the air can typically maintain round 7% extra moisture for each 1C of temperature rise.
Nevertheless, he provides that the noticed pattern in UK winter rainfall is “considerably bigger than could be defined purely by the thermodynamic course of”, and explains that pure variability can be crucial when discussing adjustments in UK winter rainfall.
“We’re in a very moist regime in the intervening time,” McCarthy explains, “so we’re seeing a lot of winter rainfall information and wetter winters, nevertheless it’s the mixture of variability and local weather change”.
For instance, December 2015 topped the charts because the UK’s wettest month on document, after Storm Desmond swept throughout the UK, bringing very heavy rainfall and gale-force winds to a lot of northern England, southern Scotland and Eire. The ensuing floods left many properties inundated and no less than 60,000 with out energy.
The winter of 2015-16 was additionally the third warmest on document. Preliminary evaluation carried out on the time instructed that the distinctive rainfall totals have been 40% extra probably due to rising world temperatures.
The jet stream
The graph beneath reveals the connection between temperature and rainfall, the place heat and moist winters are proven within the prime proper, whereas cool and dry winters are within the backside left. Darker dots point out more moderen years.
The UK’s winter climate regime is strongly linked to the energy of the jet stream. This skinny, quick flowing ribbon of air within the troposphere – the bottom layer of the earth’s ambiance – acts to steer climate methods in direction of the UK.
A robust jet stream brings heat and damp winds to the UK from the west, leading to a heat and moist winter.
For instance, the winter of 2023-24 has already been dominated by a collection of storms. Storm Jocelyn, which swept throughout the UK on the finish of January 2024, was the tenth named storm of the season. “The storms have primarily been pushed by a robust jet stream,” BBC Information reported.
Equally, in the course of the winter of 2013-14, a collection of storms introduced record-breaking rainfall to the UK, clocking in because the wettest and eighth-warmest winter on document within the UK. Intense rainfall led to “remarkably widespread and chronic flooding”, in line with the Met Workplace. Round 18,700 insurance coverage claims associated to flooding have been filed throughout the UK within the aftermath of the storms, costing an estimated £451m.
One examine means that local weather change made the sustained moist and stormy climate seen round 43% extra probably, and put an additional 1,000 homes liable to flooding alongside the River Thames.
The examine attributes about two-thirds of the rise in probability to the ambiance with the ability to maintain extra moisture as a result of the world is warming up and the remaining third to the place of the jet stream.
Conversely, a weak jet stream permits chilly air from the Arctic and mainland Europe to enter from the east and north. “A slower, extra buckled jet stream may cause areas of upper strain to take cost, which generally brings much less stormy climate, gentle winds and dry skies,” the Met Workplace says.
This was the case within the winter of 2009-10, which clocked in because the eighth-coldest and least-windy UK winter on document.
Typically, the jet stream may even get “caught” – a phenomenon referred to as blocking – and as a substitute of shunting climate methods from west to east, it may possibly enable a spell of chilly, dry climate to take a seat over the UK for a lot of days.
Whereas there’s a clear pattern of UK winters getting hotter and wetter, the information on wind velocity is much less clear-cut. Nevertheless, cool climate within the UK is commonly related to low speeds, whereas heat climate is commonly introduced by sturdy gusts.
The plot beneath reveals common UK winter wind velocity over 1969-2021 in knots. The darker line reveals the 10-year rolling common, and essentially the most and least windy years are proven by crimson and blue dots, respectively.
Windiest wintersLeast windy winters
YearsAverage windspeed (knots)YearsAverage windspeed (knots)
11973-7413.082009-107.90
21989-9012.772010-118.62
31974-7512.722005-068.81
41994-9512.712008-099.03
52013-1412.471984-859.04
61982-8312.411976-779.31
71980-8112.242018-199.32
81999-200012.112000-019.54
91988-8912.111986-879.59
102019-2012.082016-179.68
Windiest and least windy 10 winters within the UK since 1969. The darkish blue line reveals winter common wind velocity, and crimson and blue dots point out the windiest and least windy particular person winters. The gray dashed strains the typical wind velocity in the course of the windiest and least windy winters on document. The desk beneath reveals the dates and wind speeds of those winters. Credit score: Chart by Carbon Transient, primarily based on the Met Workplace HadUK dataset.
The desk beneath reveals common UK wind velocity totals for 3 overlapping 30-year time intervals.
30-year averagesAverage wind velocity (knots)
1971-200011.06
1981-201010.60
1991-202010.55
Common winter wind velocity for overlapping 30-year time intervals, from 1971 to 2020, utilizing the December-February common of imply month-to-month temperatures.
McCarthy tells Carbon Transient that there was a notable decline in UK wind velocity when taking a look at annual information, which is in step with the pattern of “stilling” – a slowdown in close to floor wind speeds – measured globally. Nevertheless, he says that this pattern is much less apparent within the winter-only information.
In the meantime, the UK State of the Local weather report 2022 states that there are not any compelling tendencies in storminess when contemplating most gust speeds during the last 4 a long time.
A variety of different atmospheric circulation patterns may affect UK winters.
The North Atlantic Oscillation (NAO) is a large-scale atmospheric strain see-saw within the North Atlantic area, which describes the distinction in air strain between the excessive strain sitting over the Azores, to the west of Portugal, and the low strain over Iceland.
When the NAO is “constructive” and the strain distinction is stronger than traditional, the jet stream shifts in direction of the poles, bringing gentle, moist and windy climate to North American and Eurasian winters and leaving the Arctic very chilly.
When it’s “destructive” and the strain distinction weakens, storm tracks shift in direction of the equator, bringing chilly, dry and calm winters to Europe.
One other mechanism is the “stratospheric polar vortex”. This low-pressure climate system sits round 50km above the Arctic within the stratosphere – the layer of the ambiance above the troposphere. Its essential function is the sturdy west-to-east winds which encircle the north pole. These winds are generally known as the “polar evening jet” as a result of they solely seem in the course of the darkish Arctic winter.
As with the jet stream within the troposphere, the polar evening jet types a boundary between the very chilly Arctic air and the hotter air over the mid-latitudes. Nevertheless, if one thing disrupts the stratospheric polar vortex it may possibly weaken, reverse route and even break up into two. This may set off a “sudden stratospheric warming” occasion the place air collapses in over the Arctic, inflicting a spike in temperatures within the stratosphere – by as a lot as 50C in simply a few days.
This enables the chilly air the polar vortex was holding in to spill out into the mid-latitudes in the course of the weeks that observe. That is what brought about the “Beast from the East” snowstorm that hit the UK in 2018. (This isn’t nicely mirrored within the UK winter information, because the brunt of the storm hit in March 2018 after the tip of meteorological winter.)
Generally, nevertheless, the UK has skilled a run of gentle, moist winters in the latest decade, together with the very moist winters of 2013, 2015 and 2019. These are in step with a constructive part of the NAO and robust polar vortex, in line with the newest State of the UK Local weather report.
Projections
Because the planet continues to heat, the UK’s local weather will shift “in direction of hotter, wetter winters and warmer, drier summers”, the Met Workplace says.
The UK Local weather Projections 2018 (UKCP18) is a collection of local weather change projections for the UK produced by the UK Met Workplace, profiting from the newest noticed information and local weather fashions
The projections embody temperature and rainfall adjustments – for averages and extremes – for every month and season of the yr, and for various emissions eventualities and future time intervals all through this century.
The maps beneath present the probabilistic projections for summer time common temperature (prime) and winter precipitation (backside) within the 2080s underneath the RCP4.5 emissions pathway, relative to a 1961-90 baseline. On this pathway, world temperatures are projected to rise by round 2.7C of warming above pre-industrial ranges by 2081-2100, which is broadly consistent with the trajectory underneath present world insurance policies.
The three percentiles (tenth, fiftieth and ninetieth) replicate the probability of these temperatures and rainfall anomalies occurring. The fiftieth percentile (center maps) is the “central estimate” throughout the fashions, whereas the tenth (left) and ninetieth (proper) percentiles replicate the bottom 10% and highest 10% of the mannequin outcomes.
The desk beneath reveals UKCP18 projections for adjustments in common UK winter temperature and precipitation underneath RCP4.5, underneath the tenth, fiftieth and ninetieth percentile, for 2080-99, in comparison with a 1981-2000 baseline.
tenth percentile change50th percentile change90th percentile change
Change in common winter temperature (C)+0.7+2.0+3.5
Change in common winter precipitation (%)-2.0+11.0+25.0
Supply: UKCP18 Key outcomes spreadsheet
As a central estimate, these projections counsel that by 2080-99, UK winters can be 2C hotter and 11% wetter than they have been in 1981-2000.
Nevertheless, the image is extra advanced for wind velocity. The Met Workplace explains that storms within the UK are influenced by components together with sea floor temperatures, Arctic sea ice soften and the jet stream.
It says that “underneath local weather change a few of these influences will strengthen storms and others weaken them, in addition to probably change the components of the world that storms have an effect on”.
It provides:
“UKCP18 projected a rise in close to floor wind speeds over the UK for the second half of the twenty first century for the winter season when extra vital impacts of wind are skilled. Nevertheless, the rise in wind speeds is modest in comparison with pure variability from month to month and season to season, so confidence is low.”
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