The averaging period used for the following assessment was 1971-2000.
The first half of May was characterised by cool weather, with a north-easterly or northerly airstream. There were showers, especially early on and over Scotland and Northern Ireland, and some frosts. Temperatures recovered during the second half of the month, with a very warm spell from 20th to 24th, when some new temperature records for May were set in Scotland. Mean temperatures for the month ended up close, or slightly below, to normal. May saw below average rainfall across almost all of the UK, with less than 50% of normal in much of western Scotland and central southern England and in a broad swathe from East Anglia to Cumbria. It was the driest May across the UK since 1991. Sunshine totals were close to, or a little above, normal.
A maximum temperature of 28.9 °C was recorded on 24th at Oxford. A minimum temperature of -6.0 °C was recorded early on 8th at Braemar (Aberdeenshire) and on 12th at Altnaharra (Highland). In the 24 hours ending at 0900 on 2nd, 60.2 mm of rainfall was measured at Golders Hill Park (Greater London).
England diary of highlights
The first half of May saw cool weather, with a mainly northerly or north-easterly airstream. After a showery first few days, there was plenty of fine weather but with some overnight frosts. Temperatures recovered during the second half of the month, with a very warm spell from 20th to 24th. Overall, mean temperatures were normal or slightly below the 1971-2000 normal, by about -1.0 °C in parts of south-east England. May was a dry month in all areas, with less than 50% of the average rainfall recorded in a broad swathe from Cumbria to East Anglia and in parts of central southern England. It ranks tenth-driest in a 100-year series, and is the driest May since 1991. Sunshine totals were up to 10% above normal.
1st to 13th:
The weather was cool throughout, with high pressure over the Atlantic bringing northerly or north-easterly winds across the country. Daytime temperatures were mainly below average and overnight it became cold enough for frost in places, most notably on the night of the 12th/13th when Redesdale Camp (Northumberland) recorded -4.9 °C, Leeming (North Yorkshire) -3.5 °C and Benson (Oxfordshire) -2.8 °C. Although there was plenty of dry weather, there were also showers or longer periods of rain at times. For example, overnight on 1st/2nd over 20 mm of rain was recorded in the London area and across the south Midlands, with 51.0 mm at Hampstead (Greater London) and 40.0 mm at Hereford.
14th to 16th:
The middle of May saw a transition to warmer weather. Rain pushed into western areas on 14th but died away. There were showers and rain on 15th and 16th, but by the end of 16th pressure had begun to build from the south-west. Temperatures rose closer to normal, with Heathrow (Greater London) reaching 17.9 °C on 15th and Marham (Norfolk) 18.3 °C on 16th.
17th to 24th:
High pressure dominated the weather with temperatures gradually rising each day, to peak at 28.9 °C at Oxford on 24th - the hottest day of the year so far. Most places remained largely dry throughout although showers did develop at times with some of these becoming thundery. Whilst many parts enjoyed prolonged sunshine, some coastal areas saw low cloud and fog, these mainly affecting western coasts at first then eastern coasts later in the period.
25th to 31st:
Although the far south had another warm day on 25th, the trend for the last few days was a return to cooler and less settled conditions. High pressure retreated into mainland Europe and areas of low pressure brought wetter, windier, cooler weather to most parts. Although the Bank Holiday weekend saw some persistent, mainly light, rain on 29th, drier weather then returned to many parts.
Wales diary of highlights
The first half of May saw cool weather, with a northerly or north-easterly airstream. There were several showery days and some cold nights. Temperatures recovered during the second half of the month, with a very warm spell from 21st to 23rd. The last week of the month was cooler and less settled again. Overall, mean temperatures were close to, or slightly below, the 1971-2000 normal. May was a dry month in almost all areas, with less than 75% of average rainfall recorded across most of Wales. Sunshine totals were up to about 10% above normal.
1st to 13th:
Heavy slow-moving showers affected much of Wales at first but with some sunshine and a cool northerly breeze. The maximum temperature at Pembrey Sands (Carmarthenshire) on 2nd was only 13.5 °C and a cold night followed, with a frost in mid-Wales. Although it remained dry on 4th, further rain then showers spread down from the north-west on 5th. Some of the showers on 6th were particularly heavy and it became quite cool by 8th with a chilly north-easterly wind. Further showers broke out until 13th with cold nights and a touch of frost inland, especially on the morning of 12th when -4.3 °C was recorded at Sennybridge (Powys). Heavy showers occurred across Powys and the Brecon Beacons on 13th.
14th to 18th:
The weather became more settled from 14th with a couple of dry days, but a few showers developed on 16th across mid and South Wales for a time. It stayed dry until later in the evening on 18th when a band of cloud and rain spread in from the west overnight.
19th to 20th:
Warmer weather arrived on 19th but with outbreaks of rain and drizzle. It stayed mild overnight with further cloudy conditions on 20th and some drizzle around western hills and coasts.
21st to 25th:
High pressure built across the country by 21st giving some dry and warm weather with temperatures climbing to over 21 °C widely. It continued warm and sunny, with 26.6 °C recorded at Trawsgoed (Ceredigion) on 22nd and 24.9 °C at St Athan (Glamorgan) on 23rd. It remained dry but became cooler on 25th as winds turned into the north.
26th to 31st:
Showers broke out across the north on 26th and in most other parts on 27th. It remained cool with a northerly breeze. Although 28th was dry, further rain spread in on 29th. It became quite windy on 30th with some heavy showers. The month ended with some sunshine, before cloud spread eastwards.
Scotland diary of highlights
The first half of May saw cool conditions, with a northerly or north-easterly airstream, and there were several showery days and some overnight frosts. Temperatures recovered from mid-month, with a very warm spell from 20th to 23rd. The last week saw a return to near-normal temperatures with occasional rain or showers, mainly in the west and north. Mean temperatures for the month were close to, or slightly below, the 1971-2000 normal. May was a dry month across western Scotland and the Borders, where only about 50% of the average rainfall was recorded widely, but totals were close to normal towards the north and north-east. Sunshine amounts were close to, or somewhat above, normal.
1st to 8th:
Rather cloudy on 1st with scattered light showers. Rather cloudy and cool on 2nd with scattered light showers. A frosty start to 3rd, with -3.8 °C at Tyndrum (Stirling), followed by sunny spells and occasional showers before patchy rain reached the north-west later. The 4th was generally rather cloudy with outbreaks of mostly light rain. On 5th, coastal areas were cool and cloudy with mist and fog patches but places inland were brighter with some sunny spells, Bishopton (Glasgow) reaching 18.7 °C. Some rain at first on 6th then mainly dry and bright but showers developed in the evening. 7th started cloudy with a little light rain, then dry with plenty of sunshine. The 8th was a dry and bright day with plenty of sunshine.
9th to 12th:
Mainly dry and bright over the south on 9th but scattered showers developed in the north, and northerly winds meant temperatures rose no higher than 7.0 °C at Lerwick (Shetland). Another cold day on 10th with frequent showers in north, wintry even to low levels. A frosty start in places on 11th, with -3.7 °C at Tyndrum, then a bright day with further wintry showers. Another frosty start on 12th, with -6.0 °C at Altnaharra (Highland), followed by sunny spells and occasional showers across southern and eastern areas.
13th to 23rd:
Rain or showers in north-west died out early on 13th before light rain spread eastwards during the afternoon and evening. Sunny intervals and scattered showers on 14th, the showers thundery at times over Moray. Sunny intervals and scattered showers on 15th then rain over the south in the evening. Sunny spells with a few showers on 16th and 17th. Dry with plenty of sunshine on 18th and temperatures widely reaching 19 °C. Rather cloudy but warm on 19th, with outbreaks of rain in the west and some sunny spells in the east. On 20th it was mainly dry with some sunshine, Leuchars (Fife) reaching 22.4 °C. The 21st was very warm with sunny spells, 24.6 °C being recorded at Strathallan (Perthshire) and 20.1 °C at Kirkwall (Orkney), the warmest May day there for 28 years. There were also thundery showers, producing 44.6 mm at Aboyne (Aberdeenshire). On 22nd mist and fog cleared to leave a warm sunny day, although isolated showers affected the north-east. The highest ever May temperatures were recorded at Leuchars (26.2 °C) and Charterhall, Borders (25.7 °C). During 23rd it was cool and misty across parts of the north and west, but bright elsewhere with heavy showers, some thundery; 25.2 °C was recorded at Gogarbank (Edinburgh) and 25.0 °C at Eskdalemuir (Dumfries and Galloway).
24th to 31st:
Bright or sunny spells and showers on 24th and 25th. On 26th, showers in the north at first developed widely, some thundery. On 27th, rain moved south-eastwards and turned showery, with thunder and hail reported widely. On 28th, showers in north at first with more persistent rain here later, and a few showers developed elsewhere for a time. Rain edged south and eastwards through 29th, although many places remained dry and bright. Dull and wet in the east at first on 30th with 26 mm at Kinloss (Moray) in the 24 hours to 0900, but brighter in the west. A fine day to end the month, with plenty of sunshine.
Northern Ireland diary of highlights
The first half of May saw cool conditions with a northerly airstream. The weather was often showery and there were some overnight frosts. Temperatures recovered during the second half of the month, with a very warm spell from 20th to 23rd. Mean temperatures for the month were close to the 1971-2000 normal. May was a dry month, with less than 75% of the average rainfall recorded in most areas. Sunshine totals were about 10% above normal.
1st to 9th:
Bright or sunny spells on 1st with a few light showers. Showers at first on 2nd then drier and brighter in the afternoon but with temperatures generally no higher than 11 °C. Occasional showers across western counties through the morning of 3rd otherwise dry with sunny spells. Rather cloudy on 4th with a few light showers. Cloudy on 5th with some persistent rain overnight, the rain becoming lighter and patchier soon after dawn. Cloudy with some patchy rain at first on 6th and light showers in the evening. Most places were dry on 7th and 8th with sunshine. Dry again on 9th with a sunny start, becoming cloudy.
10th to 15th:
Cold and rather cloudy on 10th with a few showers, and a maximum temperature of only 7.7 °C at Ballypatrick Forest (County Antrim). Locally frosty starts to 11th and 12th, with -3.7 °C and -3.1°C respectively at Katesbridge (County Down), followed by bright days and occasional showers. A bright start to 13th before patchy light rain spread in during the afternoon. Bright intervals and scattered showers on 14th. Scattered showers on 15th then more prolonged rain in the evening, heavy at times.
16th to 24th:
Some bright spells and further showers during 16th. Most places were dry on 17th with some sunshine. Dry for much of 18th with some hazy sunshine, and the temperature reached 19.8 °C at Ballykelly (County Londonderry). It became cloudy with rain edging in from the west during the evening. Rather cloudy but warm on 19th with rain at times, most persistent through the early hours. The 20th saw some sunshine, lifting the temperature to 22.2 °C at St. Angelo (County Fermanagh) and falling no lower than 15.2 °C there overnight, a station record for May. The 21st was very warm with isolated showers and Ballykelly equalled its May record of 24.6 °C. Early mist and fog on 22nd cleared to leave a dry, sunny day with a high of 24.8 °C at Katesbridge. Similar on 23rd, when Helens Bay saw 26.0 °C, and another bright day on 24th but not quite so warm.
25th to 31st:
Dry and bright on 25th, with maximum temperatures ranging from 17.3 °C at Killowen (County Down) to only 10.4 °C at Ballypatrick Forest. Scattered showers developed on 26th. Showers developed widely during 27th, before dying out during the evening. Scattered showers on 28th, and rain spread north-eastwards on 29th with drier conditions following through the evening. Mainly dry and bright with sunny spells on 30th and again on 31st, before rain spread from the west during the evening.