The UK winter of 2009/2010 compared with severe winters of the last 100 years

Authors


When severe British winters of the last 100 years are considered, those of 19631 and 1947 are usually the first that come to mind. More recent candidates include 1979 and 1982. Should winter 2010 now also be added to this list? To assist with a ranking in terms of temperature (maximum, minimum and mean), we can analyse monthly series from 1910 and daily series from 1960, based upon 5km grids. These series were assembled using the methods of Perry and Hollis (2005) and have been used to create (i) areal values for the UK, England, Wales, Scotland, Northern Ireland and regions and (ii) colour-shaded maps. The monthly Central England Temperature series from 1659 provides a longer-term perspective (Manley, 1974). For snowfall, there are monthly 5km grids of days with snow lying from 1961 (based upon 0900 utc station observations), as well as station records of snow depth at 0900 utc, mostly digitised from 1959.

Winter 2010 – overview

Winter 2010 was characterised by prolonged cold spells, hard frosts and frequent snowfalls, particularly across the northern half of the UK. After the cold weather arrived in mid-December, milder interludes were short-lived and mainly in the south. Weather patterns were dominated by winds with easterly or northerly components bringing cold air from northern Europe. Pressure was often relatively low over the UK and wintry precipitation resulted.

The combination of sustained low temperatures and deep snowfalls resulted in numerous widespread impacts. Everyday life and businesses were affected in most parts of the UK at various times from mid-December until late February, and the emergency services and local authorities were put under pressure. The adverse impacts included:

Travel delays

There was frequent disruption to road transport, with higher routes closed, jack-knifed lorries and abandoned vehicles. Motorists were occasionally stranded overnight. Rail services were also affected, an example being services through the Highlands in late February. Flights suffered delays, cancellations and diversions, with every major airport affected by snow and ice at least once during the winter.

Accidents on icy roads and pavements

Many people sustained injuries through slipping on icy surfaces and in traffic accidents, with several fatalities. For example, just before Christmas, rain falling on frozen surfaces caused problems for drivers in counties bordering the English Channel with 40 accidents on the icy A35 in Dorset.

Disruption to electricity and water supplies

Snow and ice brought down trees and power lines, cutting electricity supplies. For example, on 25 February some 45 000 homes were affected across central and northern Scotland. Water supplies to thousands of homes and businesses were also interrupted due to frozen/burst pipes.

School closures

Disruption to transport and power supplies forced the closure of many schools, including several thousand across the UK in early January.

Avalanches

A number of large-scale avalanches occurred across the Scottish mountains (see photograph on page 14) with several fatalities. Substantial avalanches were also reported from Snowdonia in mid-January and the Lake District in late February.

Winter 2010 – temperature

The UK winter mean temperature was 1.6°C, 2.0 degC below the 1971–2000 average. Winter mean temperatures for England (anomaly −1.9 degC), Wales (−2.0 degC), Scotland (−2.3 degC) and Northern Ireland (−2.3 degC) were all well below average.

Overall, the winter was most severe in northern parts of the UK, with the mean minimum temperature in the central Scottish Highlands at least 3 degC below the seasonal average (Figure 1(a)). Long nights, clear skies, deep lying snow, local topography and distance from the sea resulted in temperatures regularly falling well below −10°C in the Scottish glens. Minimum temperatures were also at least 2 degC below the seasonal average across most of Wales and Northern Ireland, and they were also well below average in England, albeit to a lesser extent in the east. Maximum temperatures were lowest across a broad swathe of northern and eastern England and Scotland, with the south and west tending to be less cold (Figure 1(b)).

Figure 1.

Winter 2010: (a) mean daily minimum and (b) mean daily maximum temperature (1971−2000 anomaly values).

The coldest periods were in the second half of December and the first half of January (Figure 2). Temperatures in the Highlands dropped to −14°C or below each night from 22 to 30 December, with −18.4°C recorded at Braemar (Aberdeenshire) (Figure 3) early on the 29th; the temperature there had risen no higher than −9.7°C the previous afternoon.

Figure 2.

Winter 2010 daily mean temperature for (a) the UK; (b) England and Wales, Scotland, and Northern Ireland.

Figure 3.

Map showing the location of places referred to in this article.

The coldest spell was in early January, when many places across the high ground of Wales and northern Britain saw temperatures failing to rise above freezing for a week or more. The night of 6/7 January was very cold across England and Wales, with −17.7°C recorded at Benson (Oxfordshire) and −16.0°C at Yeovilton (Somerset) – in each case the lowest temperature since January 1982 (Table 1). Lying snow would have contributed significantly to these very low temperatures, by reflecting solar radiation by day and reducing the upward heat flux from the ground at night. Local topography was also a factor – these minima were quite localised with temperatures at neighbouring stations more typically −7 to −10°C. The following night, 7/8 January, was again extremely cold, particularly over Scotland where Altnaharra (Highland) recorded −22.3°C, the lowest UK reading since December 1995. In the last twenty years, temperatures in the UK have rarely fallen below −20°C, the only occasions being 2 and 3 March 2001 and 27–30 December 1995 at several Scottish stations. However, temperatures below −20°C were recorded during five winters in the 1980s. The reading of −13.0°C at Lough Fea (County Londonderry) on 9 January was the lowest temperature in Northern Ireland since March 2001, when −14.8°C was recorded at Katesbridge (County Down). The maritime influence tends to prevent very low temperatures in Northern Ireland, with −20°C never having been recorded.

Table 1. Lowest air temperatures (°C) of winter 2010 for each UK region (the boundaries of these regions are shown in Figure 3).
RegionNameDateMin. Temp.Coldest sinceMin. Temp.Comments
  • 1

    The UK record is shared with Braemar, Aberdeenshire on 10 January 1982 and 11 February 1895.

  • 2

    Woodford opened in 2003. The record at nearby Ringway is −13.9°C on 25 January 1945.

  • 3

    Llysdinam opened in 1882. Records have been digitised back to 1988.

  • 4

    The English record of −26.1 °C was set during this spell, at Newport, Shropshire on 10 January 1982.

  • 5

    Lough Fea opened in 1965. Records have been digitised back to 1988.

North ScotlandAltnaharra8 January−22.3December 1995−27.2−27.2°C on 30 December 1995 is the UK record1
East ScotlandBraemar9 January−19.8December 1995−23.830 December 1995
West ScotlandEskdalemuir7 January−15.1February 1986−16.522 February 1986
Northeast EnglandKielder Castle8 January−14.2March 2001−17.12 and 3 March 2001
Northwest EnglandWoodford7 January−17.6Coldest on record2−13.925 January 1945
North WalesLlanarmon Dyffryn Ceiriog8 January−14.5January 1987−15.712 January 1987
South WalesLlysdinam8 January−16.2New record in digital archive:−18.028 November 20103
MidlandsBenson7 January−17.7January 19824−18.714 January 1982
East AngliaSanton Downham8 January−11.1January 2002−11.82 January 2002
Southeast and central southern EnglandLacock8 January−11.9January 1987−12.113 January 1987
Southwest EnglandYeovilton7 January−16.0January 1982−16.114 January 1982
Northern IrelandLough Fea9 January−13.0Coldest in digital archive5−11.227 December 1995

The second half of February was again very cold across Scotland, with temperatures in the Highlands dropping below −15°C each night from 18 to 24 February and Braemar recording −19.2°C early on the 23rd.

Notably low daytime maxima included −7.0°C at Strabane Carricklee (County Tyrone) on 24 December, −9.7°C at Braemar on 28 December, and −5.6°C and −5.5°C on 7 and 8 January respectively at Carlisle (Cumbria). Elsewhere across the UK, daytime temperatures also frequently failed to rise above freezing, significantly prolonging the period of lying snow.

Winter 2010 – snowfall

Widespread significant snowfalls occurred several times throughout the winter. They first affected eastern England on 17 December and during the next few days spread to most of the UK, particularly northern, central and eastern England, Scotland and Northern Ireland. Further heavy snowfalls affected central and northern Scotland in late December with depths of more than 30cm.

From 4 to 6 January, most parts of the UK again experienced heavy snow with falls of 10 to 20cm widely and more than 20cm across central southern England (28cm at Odiham (Hampshire) on the 6th). By 7 January the UK was almost completely covered by lying snow, deep in many northern areas (55cm at Oyne (Aberdeenshire), 57cm at Westgate (County Durham) and 60cm at Blythe (Berwickshire) on the 7th) (see photograph on page 14). Further heavy falls occurred across southwest England and south Wales on 12 and 13 January (28cm at Tredegar (Gwent) on the 12th and 25cm at Holne (Devon) on the 13th).

The second half of January and early February saw a general thaw of lying snow across southern areas, but fresh falls of 10–20cm occurred in east Kent and East Sussex on 11 February. Temperatures remained lower in the north with less thawing of lying snow, and late February saw further accumulations across northern England and Scotland. More than 30cm of fresh snow fell across the high ground of northern Scotland from 24 to 26 February (70cm lying at Balmoral (Aberdeenshire) on the 26th). The Northern Isles also experienced heavy snow, with 28cm lying at Lerwick (Shetland) on the 26th.

Time series of snow depths at stations in the Scottish Highlands, Scottish Borders, and Pennines show deep lying snow persisting from mid-December to mid-January (Figure 4). Snow depths then declined before further very heavy snowfalls affected Scotland in late February. Much of this snow had thawed by mid-March, except on high ground. Overall, the Grampian Mountains, Southern Uplands and north Pennines experienced most snow, lying for more than 60 days. In contrast, south Dorset and parts of Cornwall experienced few days with lying snow (Figure 5(a)).

Figure 4.

Snow depths recorded at 0900 utc at selected stations across (a) the Scottish Highlands and (b) the Scottish Borders and Pennines.

Figure 5.

Winter 2010: (a) days of snow lying at 0900 utc and (b) precipitation amount (% of 1971–2000 average).2

The precipitation anomaly map for winter 2010 (Figure 5(b)) shows the marked east–west contrast across the UK, consistent with the predominantly ‘easterly’ weather type and an absence of rain-bearing Atlantic frontal systems. Winter 2010 sunshine anomalies saw a similar east–west contrast, with the sunniest areas in the west and the dullest down the North Sea coast (National Climate Information Centre, 2010).

Comparison with previous winters

Comparisons for mean temperature have been made using grid-based monthly and seasonal areal series back to 1910 (Table 2).

Table 2. Rankings for monthly and seasonal areal values for winter 2010. All temperatures °C.1
 Mean Temperature1971–2000 AnomalyRank (nth coldest) in series from 1910Coldest sinceColdest in series
  • 1

    Rankings should be viewed as indicative. Uncertainties in estimating areal values may be comparable with the differences between individual years (Legg, 2011).

December 2009
UK2.1−2.010th equal1995 (1.7)1981 (0.1)
England3.0−1.721st equal1996 (2.7)1981 (0.2)
Wales3.0−1.814th equal1996 (2.6)1981 (0.8)
Scotland0.5−2.64th equal1995 (0.5)1981 (–0.7)
Northern Ireland2.4−2.34th equal1981 (1.6)1950 (1.4)
January 2010
UK0.9−2.48th equal1987 (0.7)1963 (–1.8)
England1.2−2.69th equal1987 (0.5)1963 (–2.3)
Wales1.2−2.79th1987 (0.9)1963 (–2.5)
Scotland0.3−2.110th equal1985 (0.2)1941, 1945, 1963 (–1.1)
Northern Ireland1.7−2.38th1985 (0.8)1963 (–0.3)
February 2010
UK1.9−1.619th equal1991 (1.4)1947 (–2.0)
England2.6−1.322nd equal1996 (2.3)1947 (–2.0)
Wales2.5−1.320th equal1996 (2.1)1947 (–2.3)
Scotland0.4−2.112th equal1986 (–1.2)1947 (–2.4)
Northern Ireland2.0−2.18th equal1986 (0.5)1947 (–0.5)
Winter 2010
UK1.6−2.07th1979 (1.2)1963 (–0.2)
England2.3−1.99th1979 (1.4)1963 (–0.6)
Wales2.2−2.07th1979 (1.6)1963 (–0.3)
Scotland0.4−2.32nd equal1979 (0.4)1963 (0.2)
Northern Ireland2.1−2.02nd equal1979 (2.1)1963 (1.5)

December 2009 was particularly cold across Scotland and Northern Ireland due to the very low mean daily minimum temperatures in the second half of the month. January 2010 was cold throughout the UK, whilst February was slightly milder in the south but remained cold across Scotland and Northern Ireland.

2010 was the coldest winter across England, Wales and the UK since 1979. Across Scotland and Northern Ireland, winter 2010 was comparable with those of 1979 and 1947, with only 1963 colder. While no individual month was record-breaking, it was the combination of three cold months that led to this being the equal-second coldest winter in the 100-year series for Scotland and Northern Ireland. For northern Scotland, it was the coldest winter on record and had the highest number of air frosts.

In order to place winter 2010 into the context of an even longer period, the Central England Temperature (CET) series has been used. CET is representative of an area from the south Midlands to Lancashire and has been produced using observations from a small number of stations: three in recent years (Manley, 1974). Mean monthly and seasonal temperatures have been calculated from 1659. The mean CET for winter 2010 was 2.4°C, making it equal 54th coldest in the 351-year series and the coldest since 1979 (Table 3). Only winters 1740 (−0.4°C) and 1684 (−1.2°C) were colder than winter 1963 in central England. Winter 1947 was also particularly severe, as was, more recently, 1979.

Table 3. Mean CET (°C) for winters in the last 100 years that are colder than 2010.
WinterMean CET1Rank (nth coldest)
  • 1

    Values are rounded to the nearest 0.1°C.

1963−0.33rd
19471.1= 12th
19171.5= 23rd
19401.5= 23rd
19791.6= 28th
19291.7= 30th
19422.2= 44th
20102.4= 54th

Winter 2010 has also been compared with previous winters in terms of both the persistence and depth of snow (Tables 4 and 5). Records of snow depth at 0900 utc each day have been digitised from 1959.

Table 4. Number of days with snow lying1at 0900 utc for winters from 1962 for the UK and constituent countries, in rank order. Figures in brackets are the numbers of days of air frost. 2010 figures are shown in bold.
WinterUKWinterEngland and WalesWinterScotlandWinterNorthern Ireland
  • 1

    Based on 5km gridded data from 1962. ‘Snow lying’ means snow covering at least half the ground. The table includes the first three ranked winters for air frost for each country.

196347 (68)196351 (73)196346 (62)201025 (49)
197935 (58)197932 (58)201046 (61)197920 (50)
201031 (52)198225 (43)197944 (61)196320 (56)
198227 (44)201023 (47)197737 (55)198418 (29)
198624 (46)198522 (47)198636 (51)198216 (36)

Across England and Wales, winter 1963 had the most days with snow lying, followed by 1979, with 2010 similar to 1982 and 1985 (Table 4). The winters of 1963, 1979 and 2010 were all comparable across Scotland. However, winter 2010 saw the most days of snow lying across Northern Ireland. Examination of station records for December 1946 to February 1947 published in the Monthly Weather Reports (Meteorological Office, 1947) suggests that the approximate numbers of mornings with snow cover during those three months were 35 over England and Wales, 30 over Scotland and 20 over Northern Ireland (but snow lay for a further 10 to 20 days in March 1947 in areas well away from the south coast). Winter 1963 saw the most days of air frost in all countries, although in Scotland winters 2010 and 1979 were comparable to 1963.

Across the UK, winter 1963 saw significant snow lying for at least twice as long as in any other spell in the last 50 years, with the exception of the northwestern parts sheltered from easterly winds by high ground (Table 5). The prevalence of snowy winters between 1979 and 1991 is apparent, followed by a 19-year break to winter 2010.

Table 5. The 10 ‘snowiest’ spells since 1960 – the number of consecutive days of snow lying with depths of 10cm or more at five or more stations1 The longest spell in each region is shown in bold.Thumbnail image of

Across northern and eastern Scotland and northeast England, the spell in winter 2010 was broadly comparable to those in February 1986, January/February 1984 and December 1981 to January 1982. Across the Midlands and southern England, the winter 2010 spell was comparable to February 1991, January 1987 and January/February 1985. Western parts of the UK generally saw less snow.

The winters of 1947 and 1963 feature prominently in the temperature and snow analyses and were the most severe UK winters of the last 100 years. Winter 1979 was the most recent winter that was colder than 2010. These three winters are described in more detail below.

The winter of 1947 was notable for a succession of snowstorms from late January until mid-March (see cover photograph of this issue), mainly associated with easterly airstreams (Douglas, 1947; Roberts, 2003; Booth, 2007). It has been judged to be the snowiest winter since at least the mid-nineteenth century, when reliable records began (Shellard, 1968). There were six weeks of continuous snow cover over most of the UK, and level snow depths exceeded 30cm, even in lowland areas – for example, 51cm at Cranfield (Bedfordshire) on 6 March. In upland areas depths were even greater with 112cm at Forest-in-Teesdale (County Durham) on 6 February and 91cm at Lake Vyrnwy (Powys) on 6 March. The snowfalls were accompanied by some very low temperatures, at times falling to −15 to −20°C. Strong winds caused severe drifting, up to 5m in some areas, with widespread dislocation of road and rail transport. The snowfalls prevented the movement of coal, upon which the UK was almost entirely dependent to heat homes and generate electricity. Power supplies to homes and industry were severely affected and in turn unemployment rose. Winter 1947 was also very dull: for example Kew Observatory (Surrey) recorded no sunshine from 2 to 22 February. When the snow finally melted in the second half of March, serious flooding occurred – for example along the Severn valley (Roberts, 2003). This was a time of considerable hardship and austerity following the Second World War.

The winter of 1963 was one of the most severe on record in the UK (Booth, 1968; Shellard, 1968). It was probably the coldest since 1740 over England and Wales, since 1879 over Scotland and since 1895 over Northern Ireland. The outstanding feature was its duration – from late December until early March. Mean winter temperatures were around 4 degC below average across much of England and Wales, and at many stations it was the coldest winter since records began. The winter was characterised by frequent easterly winds, with gales at times, and was cold enough for the sea to start to freeze in some sheltered locations, such as estuaries (Figure 6). There was continuous snow cover over most of the country during January and February, with several blizzards, accompanied by deep drifting, bringing road and rail transport chaos. A snowstorm on 6/7 February resulted in a reported level depth of 1.6m at Tredegar in south Wales. Even so, while the duration of snow lying in 1963 was greater than in 1947, the overall quantity of snow has been judged to be less. In contrast to winter 1947, winter 1963 was also sunnier than average, particularly in western areas, which to some extent mitigated the cold easterly winds.

Figure 6.

Ships laid up in the River Blackwater, Essex coast, in the icy winter of 1963, looking towards the Tollesbury shore. The boats from Mersea were unable to get out to the ships and the watchmen had to be supplied by helicopter. (Courtesy Mersea Museum – Ashley Upsher Collectionhttp://www.merseamuseum.org.uk/mmshipping.php)

During the winter of 1979, very cold conditions set in towards the end of December 1978 (Burt, 1980). The snow that fell after Christmas persisted and was added to throughout January and February, particularly in upland areas of the north. Winter 1979 also saw some very low temperatures, with −24.6°C at Carnwath (Lanarkshire) on 13 January, the lowest temperature recorded anywhere in the UK since February 1955. Over England and Wales, January 1979 is ranked third coldest in the last 100 years, with only 1940 and 1963 colder. However, winter 1979 was noteworthy neither for the degree of cold (surpassed in 1963) nor the snow depths (surpassed in 1947) but for the number of days with snow cover. Upland areas experienced over 50 days with lying snow as did some areas in the Midlands and eastern England. For example, in the Pennines, Great Dun Fell (847m) reported snow lying continuously from the last week of November until the first week of May.

Summary

Winter 2010 will be remembered for its prolonged cold spells, low temperature extremes and disruptive snowfalls. The spell of freezing and snowy conditions from mid-December to mid-January affected almost all areas of the UK. It was a particularly long and hard winter across Scotland, Northern Ireland and upland areas of northern England, which saw further low temperatures and snowfalls in February. Two photographs of its effects can be found on page 14.

It was the coldest winter for 31 years – since 1979 – for the UK overall and for England and Wales. When compared with winters in the last 100 years, the season is ranked seventh coldest over the UK and equal-eighth coldest over England and Wales. However, winter 2010 was particularly notable across Scotland and Northern Ireland where it was the equal-second coldest, comparable with 1947 and 1979, with only 1963 colder. Over northern Scotland, winter 2010 was even comparable with winter 1963, but elsewhere that remarkable winter comfortably retains its position as the coldest in at least the last 100 years.

The spells of snow in winter 2010 were the most widespread and significant across the UK since the mid-1980s, and 2010 sits high in lists of the snowiest winters of the last 100 years. However, over England and Wales, it was nowhere near as severe as 1947 (in terms of the quantity of snow) or 1963 and 1979 (in terms of the persistence of lying snow). The most severe conditions of the winter were in northern areas, particularly Highland Scotland which saw prolonged, deep lying snow. Across Scotland and Northern Ireland winter 2010 was comparable to, or in some areas even more severe than, these earlier winters.

An analysis of the rarity of winter 2010, based on historical records, may need to take into account the changing climate. With global warming, the probability of cold winters such as 2010 may be expected to decrease. Recent research taking into account this warming trend suggests a return period for the winter 2010 temperature of around 100 years in Scotland (van Oldenborgh, 2010). For snow cover, it is not yet possible to adjust return periods to take global warming into account: the unadjusted value for Scotland is estimated to be 20 to 50 years.

Other parts of northern Europe also experienced a severe winter 2010. For example, countries bordering the Baltic saw large negative temperature anomalies during January and February. In Ireland, it was the coldest winter since 1963, with heavy snowfalls in late December and mid-January. In contrast, with the polar jet stream displaced southwards, parts of southeastern Europe and the Mediterranean were exceptionally warm and wet. Gibraltar had its wettest winter on record with 1379mm of rainfall, easily beating the previous record of 1200mm in winter 1856 (Ball, 2011). It is interesting to note that winter 1963 was also very wet in Gibraltar (932mm).

Several winters in the last 20 years have been unusually mild. Over England and Wales, five of the ten warmest winters in the last 100 have occurred since 1990 – with 2007 the warmest of all. There has been a marked absence of widespread and persistent snowfalls in recent winters. Also, in recent decades the public has become more susceptible to travel disruption due to snow and ice – with many more vehicles on the road, longer commuting distances and more flights taken. All these factors may have affected the public perception of the severity of winter 2010, especially over England and Wales. However, over Scotland and Northern Ireland it was amongst the coldest and snowiest of the last 100 years.

Editor's note: lower temperatures were recorded in early December 2010 than in winter 2009/2010 in several parts of the United Kingdom.

Further information on the climate of the UK, including monthly, seasonal and annual summaries and statistics, is compiled by the Met Office National Climate Information Centre and available at http://www.metoffice.gov.uk/weather/uk/climate.html

  • 1

    Winter is defined in this article as the period December to February and referred to by the year in which January and February fall.

  • 2

    Maps are from gridded data produced by interpolating station values, taking into account factors such as altitude. All data have been quality controlled. Estimating precipitation totals from snow can be difficult, particularly when gauges are frozen or if snow is blown in strong winds. The ‘Days of Snow Lying’ map is based on a relatively small number of stations.

Ancillary