May 2009

The averaging period used for the following assessment was 1971-2000.

UK overview

Mean temperatures were between 0.5 °C and 1.5 °C above the 1971-2000 normal throughout the UK, with increasing warmth toward the east coast of England. Rainfall was above normal in north-west England, Northern Ireland and most of Scotland, with much of western Scotland receiving more than 150% of the long-term May average. By contrast, it was drier in the south, with parts of East Anglia and southern England receiving less than 75%. Elsewhere, rainfall was mostly close to average. Sunshine was generally around normal in the south-west, Wales, Northern Ireland and parts of northern England but above average elsewhere; indeed May was a notably sunny month across the north and east of Scotland with most parts receiving 130% or more of the normal amount.

A maximum temperature of 27.5 °C was recorded at Cae Poeth (Gwynnedd) on 31st. Drumnadrochit (Inverness-shire) recorded a maximum temperature of 27.3 °C on 29th. Kinbrace (Highland) recorded a minimum temperature of -4.7 °C on 11th. 70.6 mm of rainfall was recorded at Seathwaite (Cumbria) on 5th. A wind gust of 72 mph was recorded at South Uist (Western Isles) on 7th.

England diary of highlights

The start of May was unsettled with low pressure dominant and showers or longer spells of rain. However it was drier in the south-east. This was followed by a brief spell of more settled weather in the middle of the month before a return to generally unsettled conditions. However, high pressure re-established over the last few days of May with warm, sunny weather and increasing temperatures. Overall, May was warmer than average, particularly across eastern parts. Rainfall was above normal in the north-west, but below normal in much of southern England. Sunshine was also above normal across most of England.

1st to 3rd: A generally unsettled westerly flow, with showers and longer spells of rain, however this was interspersed with some fine weather, particularly in the south-east. These parts experienced a sunny, warm and dry day on the 1st with maximum temperatures of 21.5 °C at Weybourne (Norfolk) and 21.0 °C at Gravesend (Kent). Temperatures over much of the country were near normal for early May though feeling cooler in the breeze.

4th to 10th: The unsettled theme continued, with low pressure dominant, bringing windy conditions and frequent outbreaks or longer spells of rain. A set of fronts progressed southwards during the night of the 4th, but southern England stayed largely dry and clear with -1.0 °C recorded at Benson (Oxfordshire). Outbreaks of rain continued on the 5th, with strong gusty south-westerly winds, although bright or sunny spells developed further south. Maximum temperatures were 20.2 °C at London Heathrow and 19.7 °C at Manston (Kent). It remained unsettled on the 6th and 7th. On the 8th a band of rain moved southwards across England, followed by heavy thundery showers across northern England; the 8th was a windy day with widespread gusts of 40 to 50 m.p.h. Further rain and showers affected northern England on the 9th, but it became drier and more settled on the 10th.

11th to 17th: High pressure became established on the 11th and 12th. It was relatively warm in sheltered southern and western areas, with Hurn (Dorset) reaching a maximum temperature of 18.8 °C, but windy across the far south with 53 m.p.h. recorded at Culdrose (Cornwall). It was dry and largely clear overnight across northern England on the 13th with a ground frost as far south as the Midlands. Thereafter conditions became cyclonic and unsettled. Heavy and thundery showers on the evening of the 15th moved across northern England, and it became very windy across south-west England and the south coast with gusts of 45 to 55 m.p.h. A band of heavy and thundery rain spread into south-west England and progressed northward during the 17th, with some localised flooding in Southampton.

18th to 28th: Staying generally unsettled. Overnight on the 18th further bands of showery rain affected western parts of England, with heavy showers affecting the south-west and Midlands and winds gusting 40 to 50 m.p.h. A heavy downpour on 19th caused local flooding in Doncaster. It continued showery until the 23rd when temperatures increased under a brief ridge of high pressure: London recorded 25.9 °C on the 24th. It was unsettled on the 25th and further rain fell on 26th; Wainfleet and Holbeach (Lincolnshire) recorded 25.8 mm and 24.2 mm respectively, and Marham (Norfolk) 17.8 mm. This was followed by a gradual return to more settled conditions during 27th and 28th.

29th to 31st: High pressure re-established itself, with warm, dry, sunny weather and unbroken sunshine over most of England. Solent (Hampshire) recorded a maximum temperature of 26.9 °C on the 31st.

Wales diary of highlights

A changeable start to the month: windy, with showers and some longer spells of rain. A brief spell of fine, settled weather between the 9th and 12th, before a very unsettled, rainy spell from the 13th to 22nd. More settled and progressively warmer toward the end of the month, although heavy rain over the hills on the 27th. Overall, rainfall was slightly above average, although temperatures were higher than normal across Wales. Sunshine was around average.

1st to 8th: During this period a succession of weather fronts from the Atlantic moved east across Wales giving some showers and a few longer spells of rain. However, the rain was generally light and moved through quite quickly. The exception to this was on the 8th when heavy showers accompanied by local hail and thunder occurred in the morning along with strong winds gusting 40 to 50 m.p.h.

9th to 12th: A marked change from a westerly to an easterly flow with generally dry weather for a few days. There were a few showers on the 9th and 10th, but the 11th became fine and sunny though breezy especially over the south. This fine weather continued through the 12th, although the south became cloudier with a few spots of rain late in the day.

13th to 22nd: A very unsettled spell with rain moving north during the 13th followed by further areas of rain moving across from the south-west between the 14th and 18th. There were isolated thunderstorms on the 15th and it became windy on the 16th with gusts to 65 m.p.h. at Capel Curig (Gwynedd). Further heavy thundery rain occurred on the 17th. The showery, unsettled conditions continued from the 19th to 22nd.

23rd to 31st: From the 23rd it became more settled although there were a few showers on the 25th and 26th with widespread locally heavy rain especially over the hills on the 27th. From the 28th it became dry, progressively warmer and sunnier with virtually unbroken sunshine on 30th and 31st. Rhyl (Clwyd) reached 25.5 °C on the 29th, and Hawarden Airport (Flintshire) reached 25.4 °C on the 31st.

Scotland diary of highlights

It was a changeable start to the month, and very wet in the west. A brief interlude of more settled weather came between the 10th and 14th, before a return to more unsettled conditions with rain or showers. However, the last few days of May were dry, warm and sunny. Overall, temperatures were slightly above normal. May was a wet month, particularly across the high ground of the west, and rainfall was also above average in the east. A sunny month across Scotland, particularly towards the north and north-east.

1st to 9th: Either wet with spells of rain or a mixture of bright, sunny or clear spells and showers. Highlights included the windy weather on the 7th and 8th when gales occurred, locally severe on the 7th with gusts of 72 m.p.h. at South Uist (Western Isles). Thunderstorms broke out on the 8th with snow across the hills. It was wet at Prestwick (Ayrshire) on the 9th, with 16.6 mm of rainfall recorded.

10th to 14th: The weather settled down towards the middle of the month. The 10th was mainly dry and sunny, though scattered heavy showers developed, thundery through the Borders. The 11th started chilly, with -4.7 °C recorded at Kinbrace (Highland). A sunny day followed with temperatures ranging from 11 °C on the east coast to 17.4 °C at Prestwick (Ayrshire). The 12th was similar, the extremes being Aboyne (Aberdeenshire), which recorded -4.6 °C, and Kinlochewe (Highland), which recorded 19.3 °C. Patchy rain developed over the south-west during the evening on the 13th, which persisted through the 14th. Elsewhere, it was sunny, with Lusa (Skye) reaching 20.2 °C.

15th to 27th: Rain spread north on the 15th, becoming quite heavy later with strong easterly winds, and lingered in the north-east on the 16th, resulting in 20 to 30 mm in a 24-hour period. Shetland stayed fine and sunny on both days while the south and west turned bright and showery. The 17th saw a band of occasionally heavy showery rain moving north through the morning followed by another during the late afternoon/evening with sunny spells between. Again, rather cloudy on the 18th with frequent showers, some heavy with isolated thunder. Another very showery day on 19th; the heaviest showers were across Aberdeenshire and Highland with thunderstorms. The temperature at Altnaharra (Highland) reached 17.6 °C. The showery weather persisted through the 20th and 21st, again showers turning thundery across Aberdeenshire and Highland. Showers were lighter and more scattered on the 22nd, although still heavy across parts of Aberdeenshire. A band of cloud and rain pushed east through the country on the 23rd, clearing from the west later. The 24th was mainly dry, with the best of the sunshine in the east. Fyvie (Aberdeenshire) reached 19.2 °C. Patchy rain then spread to the north-west, which carried on south-eastwards through the 25th, although Charterhall (Borders) reached 21.4 °C in the sunshine. A mixture of sunshine and showers on the 26th. Rain spread south-east on the 27th, followed by sunshine.

28th to 31st: Sunshine developed after the last of the rain on the 28th, setting the scene for a dry and settled end to the month, although low cloud did occasionally affect the coasts and some inland spots too. Aberdeen recorded the highest temperature of 22.0 °C on the 28th. Kinlochewe and Cassley (both Highland) each recorded 26.5 °C on the 29th, which was the warmest day of the year so far, and Cassley recorded 26.4 °C on the 30th. Bishopton (Glasgow) was the warmest on the 31st, reaching 24.2 °C.

Northern Ireland diary of highlights

A wet and unsettled start to the month, but followed by a short spell of dry and settled weather between the 10th and 13th. A return to changeable conditions for the latter half of May, with either rain, or a mixture of sunshine and showers. However, the last few days were dry, warm and sunny. Overall, May was wetter than average, although temperatures were higher than normal for the month. Sunshine was average.

1st to 9th: The first 9 days of May were either wet with spells of rain or a mixture of bright, sunny or clear spells and showers. It was also windy on the 7th and 8th.

10th to 13th: The weather settled down towards the middle of the month. The 10th was bright or sunny with the odd shower, and St Angelo (Fermanagh) reached 16.3 °C. The 11th and 12th started chilly, each with a sunny day following. Temperatures ranged from -0.1 °C in Castlederg (Co Tyrone) on the 11th to afternoon temperatures of between 14 °C in the east and 17 °C in the west. The 13th started clear or sunny, but rain developed later.

14th to 27th: There was a return to changeable weather between the 14th and the 27th, with either rain or a mixture of bright, sunny or clear spells and showers. Thunderstorms developed through the afternoons of the 19th, 20th and 21st. There were reports of localised flooding in the Belfast area during the evenings of 19th and 20th.

28th to 31st: Rain died out through the 28th and sunshine developed. This set the scene for a dry, warm, end to the month. The morning of the 29th was dull and misty but it brightened up through the afternoon, although the low cloud and mist did persist along the Down coast. It became progressively warmer with temperatures reaching 21.3 °C at Helens Bay (Co Down), on the 28th, St Angelo (Co Fermanagh) reaching 22.9 °C on the 30th, and Castlederg (Co Tyrone) reaching 24.6 °C on the 31st, although it was cooler around Irish Sea coasts due to onshore breezes.

Last updated: 27 February 2013