The averaging period used for the following assessment was 1961-1990.
Mean temperatures ranging from close to average across north-west Scotland to over 1 °C above average across southern and eastern England. Well above average rainfall across the majority of the UK, with East Anglia experiencing its wettest May (areal series back to 1914) with over 200% of average May rainfall. Sunshine amounts varying from above average over Scotland and Northern Ireland to below average across parts of eastern England.
England diary of highlights
A wet month with some areas setting new rainfall records for the month. Temperatures above average, despite sunshine amounts below normal.
1st to 5th: High pressure close to the north of the country dominated this period, while much of nearby Europe was affected by areas of shallow low pressure. This resulted in a generally easterly airflow across England throughout the period. On the 1st and 2nd, thundery showers that formed over France during the daytime, drifted up over south-west England at times, notably at first on the 1st with around 10 mm recorded overnight on parts of Dartmoor. On the whole though, a good deal of dry, reasonably warm and sunny weather was recorded across much of England, continuing the theme from the end of April. A maximum temperature of 24.1 °C was recorded at Hurn (Dorset) on the 1st. Low cloud became and increasing problem, particularly in the east, although by the 5th, it was even slow to clear in some western parts which depressed temperatures relative to values from earlier in the week with only 15 °C recorded in parts of the southeast.
6th to 19th: Low pressure took over for much of this period. The first area of low pressure moved to the north of Scotland on the 6th and brought some showery rain to the north-west, and later the south-west as a wave developed on the associated cold-front. It became quite breezy in the south as this cleared on the 7th. The frontal zone was never far from southern England and another wave developed on the 8/9th giving parts of Dartmoor nearly 20 mm of rain. The rest of England and Wales was showery on the 10th but yet another wave in the south-west gave more rain, 19 mm at Liscombe (Devon). More rain crossed the country on the 11th and again, the southwest seemed to bear the brunt with 21 mm in parts of Cornwall. Showers, locally heavy, ensued the next day before the next area of low pressure headed up from the south-west on the 13th. After a dry start, rain reached all areas, and around 60 mm was reported in Shropshire during the day. The remnants of the rain and low pressure gradually cleared to showers on the 14th. Yet more rain crossed the country on the 15th, though cleared quickly to heavy showers, with 17 mm recorded at Brize Norton (Oxfordshire) in just 2 hours in the afternoon. The 16/17th was dominated by rather weaker frontal zones, bringing mainly light rain and drizzle, especially to western areas. It was very mild air though, and in sheltered spots some brightness was observed, and this helped Lee-on-Solent reach 23.4 °C on the 17th. The cold front cleared all this away on the 18th, with showers following for the 19th.
20th to 25th: A quieter spell of weather followed, though for much of England it couldn't, by any stretch of the imagination, be called 'fine'. A weak ridge of high pressure gave a dry day though on the 20th but a troublesome (and consequently rather persistent) frontal zone close to the south-east gave some rain in the evening here. This persisted though the 21st though northern and central parts had a drier and brighter day. The rain finally cleared the southeast on the 22nd, but at the same time some thicker cloud and patchy rain moved into the north-west. Some warm conditions developed on the 23rd/24th as a weak ridge of high pressure extended from the Azores across southern parts. 26 °C was recorded at Gravesend on the 24th. A band of light patchy rain crossed the country on the 25th, bringing an end to the warm weather in the south-east.
26th to 31st: The month ended on a more unsettled note. The 26th was showery, particularly in the north, but also in the south-east where the remnants of the previous cold front were never too far away. A deep area of low pressure wound itself up near the southwest on the 27th before moving along the English Channel later bringing some gale force gusts to Cornwall. Much of England saw rain at times, though the heaviest was always in the south with a 24 hour total of 74.8 mm recorded at St Catherine's Point (Isle of Wight). This low pressure moved only slowly east bringing another wet day on the 28th, with cold northerly winds to much of central and eastern England. The maximum temperature was only 6.6 °C at Kenley, and 54 mm of rain was recorded at Letchworth (Hertfordshire.) Heathrow airport's day-time maximum temperature of 7.9C was its 2nd coldest on record for May. A showery day followed on the 29th, though the west was largely fine. More rain spread across the country from the south-west on the 30th and with a trough of low pressure anchored across England on the 31st, widespread heavy showers formed.
Wales diary of highlights
A wet month overall, with mean temperatures above average and sunshine amounts near normal.
1st to 5th: The first few days of the month were dry and pleasantly warm, with high pressure across the north of the British Isles maintaining an east to north-east flow across Wales. Some good sunny spells occurred by day allowing temperatures to reach a maximum of 21.1 °C at Trawscoed on the 1st and 20.8 °C on the 3rd, however there was a touch of ground frost in some rural areas in east Wales on the 2nd with temperatures falling to around 2 °C.
6th to 19th: Unsettled weather dominated through this period with a succession of Atlantic lows and frontal systems tracking east across the British Isles with temperatures generally nearer normal with typical maximum temperatures of 14.5 °C at Rhyl on the 9th and 15.2 °C at Pembrey Sands on the 14th. Spells of rain or showers affected Wales on most days with the 13th being a particularly wet day with rainfall totals exceeding 25 mm in a number of places, as an area of low pressure and active frontal system tracked northeast across Wales.
20th to 24th: A ridge of high pressure finally managed to build north-east across England and Wales on the 20th, bringing a short spell of relatively sunny, dry and warm weather across Wales, with maximum temperatures reaching 20.6 °C at Sennybridge on the 23rd and 20.2 °C at Rhyl on the 24th, but minimum temperatures fell to 3 °C in places early on the 20th.
25th to 31st: The unsettled weather returned as a cold front brought cooler conditions from the north-west on the 25th. Further Atlantic lows and fronts moved in from the south-west during the last few days of the month. A relatively deep low for the time of the year moved east across the far south of England on the 27th, bringing wet and cold conditions across Wales, with a maximum temperature of 7.4 °C only being recorded at Sennybridge and Lake Vyrnwy and 24.4 mm of rain recorded at Milford Haven. Further heavy showers occurred on the 31st with 13.6 mm recorded at Capel Curig.
Scotland diary of highlights
Changeable weather throughout May after an initial dry, settled, start.
A dry spell of weather from the 1st to most of the 5th, with overnight mist, fog and frost affecting inland Highland, Grampian and Tayside, with warm sunshine by day. Cloud plagued the north and east, at times. Daytime maxima ranged from 9 °C across the Northern Isles and the East Coast to the low 20's °C in Highland with 24 °C being recorded at Dalmally on the 3rd.
Rain developed late on the 5th and cleared early on the 6th with a showery spell of weather following and this lasted until the 15th. Highlights during this period were gales on the 6th with gusts in excess of 65 m.p.h. across the Northern and Western Isles. Warm temperatures developed in the sunshine with 17 °C being recorded at Leuchars on the 9th, 15 °C at West Freugh on 13th and Leuchars on the 14th, and finally 16 °C at Glasgow Bishopton on the 15th. There were also cold temperatures with inland frosts from the 13th, with minimum temperatures between -2 °C and -4 °C and the temperature struggled to reach 8 °C at Lerwick on the 15th.
It was mostly cloudy on the 16th, with rain and drizzle in the west, but drier in the north and east with sunshine across Shetland. The 17th was rather cloudy with some patchy, mainly light, rain or drizzle around, especially in the west, but some sunny spells developed across the south and east during the afternoon. Cloud and outbreaks of rain cleared from the north-west through the morning on the 18th to leave sunny spells and locally heavy showers, frequent in the west. Strong to gale force south-westerly winds gusted to near 60 m.p.h. around the Minches and this bright and breezy weather with showers persisted through the 20th, although by that time the winds had eased.
A chilly start with some inland frost on the 21st, with a temperature of -1 °C recorded at Braemar. A bright and sunny day followed with the temperature reaching 18 °C at Lossiemouth. A spell of overnight rain cleared on the 22nd with another bright day following with showers developing across the north and north-west. The 23rd was mainly cloudy with patchy rain in west with sunny spells developing in the sheltered east and the temperature in Aberdeen reached 22 °C. Mostly cloudy on the 24th, with patchy rain moving slowly south, heaviest in the north-west. Clearer, cooler, showery weather followed overnight and this brighter, showery spell of weather persisted from the 25th to the 28th. Chilly with a local frost inland at times, air temperatures of -6 °C recorded at Kinbrace and minus -4 °C at Altnaharra on the morning of the 27th.
Heavy and persistent rain spread across the north and east on the 29th and eventually clearing north-westwards during the evening of the 30th. Dyce reported 54 mm and Tain 65 mm through the two days. However Shetland, the south-west and southern Strathclyde remained largely dry with some bright or sunny spells. Mist, fog and patchy rain affected southern Shetland, Orkney, Caithness and eastern Grampian on the 31st, where as bright or sunny spells with showers occurred elsewhere. A few thunderstorms developed across the Central Lowlands, Dumfries and Galloway and the Borders during the early evening and a waterspout was reported at Leith Docks. Kinloss recorded a temperature of 21 °C, where as Fair Isle recorded 11 °C.
Northern Ireland diary of highlights
Changeable weather throughout May after an initial dry, settled, start.
The 1st to the 4th was dry with early mist and fog patches soon clearing to leave plenty of sunshine with temperatures up to 22 °C. The 5th was mainly dry with some sunshine but cloud thickened to bring rain late in the day, still quite warm with Killowen reaching 19 °C.
There was rain during the morning of the 6th followed by brighter, showery, weather that persisted until the 15th. Highlights throughout the period were reports of a tornado at Carrickfergus on the 9th, heavy downpours on the afternoon of the 12th when St Angelo reported 11.4 mm in one hour during the afternoon and a funnel cloud was reported was above Cloughmills on the 15th. A cooler spell of weather than earlier in the month with maximum temperatures around 15 °C.
The weather turned unsettled from the 16th through to the 18th as fronts brought spells of rain with 20 mm falling at St Angelo on the 16th. When the sun did shine 16 °C was recorded at Newry on 16th and 21 °C on the 17th. Rain cleared through the first half of the morning on the 18th to leave sunny spells and showers, occasionally heavy. This showery and occasionally windy spell of weather persisted until the 20th.
A chilly start on the 21st with Katesbridge recording -1 °C, but a bright or sunny day followed with Helens Bay reaching 18 °C. Then it was back to changeable weather as fronts brought spells of rain and drizzle, mainly to the north and west with brighter conditions, at times, across the south and east.
Bright, sunny or clear spells with showers from the 25th to 29th. These showers merged to give a longer spell of rain during the evening of the 26th when Glenanne reported 15 mm over a 5 hour period. Hail showers were reported on the 28th. It remained cool with ground frosts on each night, and Katesbridge recorded -3 °C on the 29th. A bright or sunny start on the 30th, but thickening cloud brought rain during the evening, which cleared during the morning of the 31st to be followed by sunny spells and occasional showers, more so across South Fermanagh, South and West Tyrone and South Armagh.