The averaging period used for the following assessment was 1981-2010.
UK climate video
At the start of the month, the UK was in a rather unsettled weather type, with some heavy rain in western and northern areas. This set the scene for the month, with a predominantly north-westerly airflow bringing rather wet and cool conditions - especially during the first half. There were only occasional short fine spells mainly in the south. Daytime temperatures were particularly suppressed, and nowhere reached 24 °C during the month.
The UK mean temperature for May 2015 was 9.6 °C, which is 0.8 °C below the 1981-2010 long-term average. For maximum temperatures, this was the coldest May since 1996. It was coldest relative to average in northern and western areas. Rainfall was above average, with more than double the average in a number of places, and near-normal totals were restricted to southern and eastern areas. The overall UK rainfall total was 158% of average - this being the fourth substantially wetter than average May in the last five years. Sunshine was slightly below normal in many areas, especially across North Wales and Northern Ireland, and the UK received 94% of average sunshine hours.
A maximum temperature of 23.8 °C was recorded at Faversham (Kent) on the 11th. A minimum temperature of -5.6 °C was recorded at Tulloch Bridge (Highland) on the 1st. In the 24 hours ending at 0900 GMT on the 3rd, 101.3 mm of rain fell at Trassey Slievenaman (County Down). A wind gust of 75 mph was recorded at Needles Old Battery (Isle of Wight) on the 6th.
Wet weather over north-western parts of the UK on the 2nd brought some localised flooding to Northern Ireland and snow across parts of the Scottish Highlands. An area of strong winds swept along southern parts of England during the 5th and 6th, while other parts of the UK had bands of heavy rain on those two days. The Scottish Borders experienced heavy rain on the 10th.
After this, the weather was quieter until the end of the month, when strong winds from an active frontal system cleared through south-east England, albeit causing little in the way of disruption.
England diary of highlights
The month began unsettled, with spells of rain, and it was particularly windy on the 5th and 6th. Although there was some fine spring-like weather at times from around the 10th onwards, it never became really settled, and there were no notable warm spells, so it ended up being a rather cool and wet month overall.
The mean temperature for the month was 0.4 °C below the 1981-2010 long-term average; maxima were well below average towards the north-west, but minima were close to average everywhere. Rainfall was generally above average, with some places north of a line from Cheshire to Humberside receiving more than twice the normal amount, and only a few places further south and east coming in below average. The overall rainfall figure for England was 136% of average. Sunshine amounts were unremarkable, with an overall total of 96%.
1st to 9th:
After a widespread frost for northern areas on the 1st, it was bright and mainly dry, except for the south-west which remained dull with patchy rain. Rain spread from the west during the morning of the 2nd, reaching eastern areas during the afternoon, although the south remained mainly dry. A band of overnight rain cleared the east by early afternoon on the 3rd to leave a bright day, but with scattered showers, some heavy with thunder in central and eastern areas. The 4th started dry and bright, but rain slowly edged in from the south during the afternoon and made slow progress northwards during the evening. The 5th was a day of sunshine and scattered showers with a strong westerly wind, and exposed southern areas saw gusts up to around 60 mph. The 6th continued very unsettled, many areas seeing showers or longer spells of rain, and the far south-west having the best of any sunshine. With winds easing, showers were fewer on the 7th; these were mainly around the Midlands and eastern areas with many other places dry and bright. A band of rain spread from the west during the 8th reaching the north-east by late afternoon with clearer, showery conditions behind. There was patchy rain in some northern and southern areas at first on the 9th but this cleared to leave isolated showers in a fresh westerly wind.
10th to 17th:
The 10th was mainly dry and bright, and felt warmer than of late. Fine and warm with sunny spells on the 11th, and temperatures reaching 23 °C in parts of the south-east. A mainly bright day on the 12th, with only isolated showers in the north-west, although thunderstorms developed in Humberside during the afternoon. The 13th was a dry and sunny day. An area of rain spread slowly from the south-west during the morning of the 14th, crossing the Midlands and the south-east before clearing. The 15th was dry and bright for much of the day although a fragmented band of mainly light rain edged into the west during the late afternoon. A cooler day on the 16th in a north-west wind, but generally dry and bright. A similar day on the 17th with any showers restricted to the north-west.
18th to 31st:
Rain moved slowly east during the morning of the 18th, followed by a bright and breezy afternoon with scattered showers. The 19th saw some sunshine, but also widespread showers, some with hail and thunder, the heaviest ones mainly in the south and east. The 20th saw the showers restricted to eastern areas with the heaviest across Norfolk. The north had patchy light rain on the 21st, while southern areas remained mainly dry with sunny spells. The 22nd was mainly cloudy, with only isolated showers mostly in the west. Mainly dry with sunny spells on the 23rd, and warmer with temperatures up to 21 °C in Wiltshire. A fragmented band of showers spread from the north-west during the 24th, clearing the south-east by evening . A cooler day on the 25th, but mainly dry, with the best of any sunshine in the south. Another mainly dry day on the 26th with sunny spells, but again rather cool in a north-west wind. Apart from some showers in the north in the afternoon, the 27th was mainly dry and bright, with the best of the sunshine in the south-east where temperatures reached 21 °C. Overnight rain cleared from the west early on the 28th to leave a mainly dry, bright day with scattered showers. On the 29th, an area of heavy rain cleared eastwards through the morning, leaving behind strong north-westerly winds and scattered blustery showers, accompanied by hail and thunder in places. The 30th was mainly dry and bright with isolated showers but rain edged eastwards through the evening and night. On the 31st, further spells of rain for some areas in the morning cleared south-eastwards to leave a mainly dry and bright but fresh afternoon.
Wales diary of highlights
After a showery start, with strong winds on several days, the weather did improve slightly but it was generally an unsettled and cool month throughout, with only a few fine days.
The mean temperature for the month was 0.8 °C below average, with maximum temperatures particularly suppressed relative to average, but minima very near normal. Rainfall was above average, most especially around Cardiff and in the north-west, with 158% of average for Wales overall. Sunshine was rather below average, especially in the north, with 88% of average for Wales overall.
1st to 8th:
It was dry and sunny at first on the 1st but cloud increased through the day with patchy rain in the south in the afternoon and evening. Patchy rain continued through the morning of the 2nd and slowly moved north in the afternoon. The rain cleared away to the north early on the 3rd with some showers through the day. Mainly dry at first on the 4th with some sunshine, but rain moved in from the south-east by the evening. Patchy rain early on the 5th moved north to give way to showers and some sunshine in the afternoon. The 6th had rain from the west from early morning along with strong to gale-force winds but the rain became showery later and winds moderated. Sunshine and showers all day on the 7th. Rain in the west and north on the 8th spread further east in the afternoon before clearing in the evening.
9th to 17th:
Mainly dry on the 9th after a few early isolated showers, with the best sunshine in the south. Dry and cloudy on the 10th, but rain reached the far north-west by late evening. Patchy rain continued in the west into the morning of the 11th and moved east but became lighter; the rest of the day was dry with some sunshine, although it clouded over in the evening with patchy rain returning. The rain continued overnight, clearing to the east by late morning on the 12th to leave a dry and bright afternoon and evening. The 13th was dry and warm with sunshine. Cloudy on the 14th, with rain by dawn which moved north-east to cover all of Wales through the morning, but it cleared away to the east later in the afternoon. The 15th had some sunshine, along with patchy rain or showers during the afternoon. The 16th was dry and sunny, and it was fine too on the 17th with some sunshine in the morning, but rain moved into the far north-west in the evening.
18th to 31st:
The morning of the 18th was wet, but the rain cleared to showers during the afternoon. The 19th had some sunshine, but there were showers, some of which were heavy in the afternoon. Early showers on the 20th died out to leave a dry, sunny day but it was still cool for the time of year. The 21st was mainly dry and sunny with an isolated shower around midday. Mainly cloudy on the 22nd with an isolated light shower. The 23rd was dry, with more sun in the south. After patchy rain in the morning, the 24th was fine with some sunshine. Mainly dry and cloudy on the 25th after an isolated early shower. The 26th was dry with some sunny intervals, and quite warm in the south-east. Some sunshine at first on the 27th but light and patchy rain moved into the north-west during the morning, spreading to the south and east during the afternoon. The 28th had sunshine, along with some isolated showers during the morning which died out during the afternoon before persistent rain reached the far north-west in the evening. Rain in the early hours on the 29th soon cleared, giving way to sunshine and showers. The 30th was dry with sunshine until late in the day when cloud and rain moved in from the west. Rain in the early hours on the 31st cleared to sunshine and showers.
Scotland diary of highlights
The month began rather unsettled and increasingly wet, with some strong winds. There were some brief settled spells in the middle and latter parts of the month, but for much of the time it remained unsettled with large rainfall totals and it was a chilly month.
The mean temperature for the month was 1.2 °C below the long-term average, making it the coldest May since 1996. Rainfall was well above average everywhere except parts of Aberdeenshire and Inverness-shire and there was more than twice the normal in some places. The overall figure for Scotland was 180%, the fourth wettest May in a series from 1910. Sunshine totals were 94% of average.
1st to 12th:
Showers in the north-east spread erratically westwards during the 1st but it remained mainly dry in the south. Most places started dry on the 2nd, but rain spread into the southern half of the country during the afternoon. Rain, heavy at times, continued for most areas on the 3rd, clearing from the south later in the afternoon, with 36.2 mm recorded at Durris (Aberdeenshire). Rain in the far north at first on the 4th moved away, with only a few scattered showers remaining. It was wet on the 5th with rain in the south spreading to all areas through the day. Wet and unsettled again on the 6th with rain and heavy showers for most areas. Blustery showers for all areas on the 7th, especially in the north and west. Some patchy rain in the east at first on the 8th, showers developed in the north later, and an area of rain spread into the south in late afternoon. This rain cleared away from the east early on the 9th, but scattered heavy showers developed over most areas later in the day, especially towards the east. The 10th was wet for all areas with rain and strong winds. Showers or longer spells of rain for most areas on the 11th were accompanied by strong to gale-force winds. Winds were strong again on the 12th as showers and spells of rain spread east across the country.
13th to 15th:
Most areas were dry on the 13th apart from a few showers in the north. The 14th was dry too, with bright or sunny spells for most areas but more cloud in the east. After a mostly dry start on the 15th, a weather system spread eastwards across the country bringing rain to most areas by afternoon.
16th to 23rd:
The 16th was a blustery day with strong winds, and showers for most places becoming heavier and more widespread through the day. Most areas had further blustery showers on the 17th, merging into longer spells of heavy rain in the west later. A wet morning for many southern and eastern areas on the 18th but by the afternoon it was showery everywhere. Showers again for all areas on the 19th with a band of rain spreading into the north later in the day. Generally dry at first on the 20th but rain spread into the north later in the day. Some areas had rain on the 21st but it was drier in a band from Inverness down to the Borders. Rain at first on the 22nd in the north and the south-west but it became mostly dry later. The 23rd began dry for most, and it was warmer, with a maximum temperature of 18.8 °C recorded at Edinburgh Botanic Gardens, but a band of rain spread into the north-west later in the afternoon and continued south during the evening.
24th to 31st:
The north and west were showery on the 24th but most eastern areas stayed dry. Showers in the north on the 25th gradually died out by late afternoon, but it was dry, bright and warm further south. Mostly dry again in the south on the 26th with scattered showers further north. The 27th began dry in the south again, but with showers in the north, before a weather system brought rain to all areas for the afternoon. The 28th saw some sunshine but with frequent showers in the west. Sunshine and showers continued on the 29th. The 30th started sunny, with any showers confined to the north-east, but rain moved north through the afternoon. The rain was extensive and heavy across most of Scotland through the early hours of the 31st, clearing the south-west by mid-morning and the north-east by early afternoon, with sunshine and showers following behind.
Northern Ireland diary of highlights
Most of the month was unsettled and cool, with heavy rain at times and strong winds on several days, although there were one or two short drier spells.
The cool nature of the month gave a mean temperature 1.1 °C below the long-term average, the coldest May since 1996. It was also a very wet and dull month, with rainfall totalling 171% of the long-term average, and a sunshine total of only 83% of average.
1st to 8th:
The 1st was mainly fine and bright, and the 2nd began dry before rain, accompanied by strong south-easterly winds, spread in from the south, becoming very persistent and heavy. The rain continued into the morning of the 3rd, causing localised flooding, and a total of 101.3 mm was recorded at Trassey Slievenaman (County Down). It became dry for a time before showers arrived in late afternoon. The 4th was mainly dry and bright apart from some heavy showers in the west later. The 5th was another wet day with rain, heavy at times, spreading in from the south-west. Further rain overnight and at first on the 6th cleared to leave a showery day. The 7th was mainly dry and bright but with some showers later on. The 8th started dry but rain, heaviest in the east, spread in from the south in the afternoon.
9th to 14th:
It was mainly dry and bright on the 9th but with some showers later. An area of rain cleared early on the 10th but was followed by a further band of rain, heavy at times, accompanied by a strong but mild southerly wind. A bright and breezy day on the 11th brought just a few showers. There were blustery showers and sunshine on the 12th, the strong south-westerly wind gusting to gale force. High pressure then developed for a couple of days, and the 13th and 14th were largely dry and sunny.
15th to 18th:
The fine spell was short-lived, with rain arriving during the morning of the 15th but clearing during the afternoon to leave behind showers and strong westerly winds. There was some sunshine on the 16th, but blustery showers too, heavy at times but less frequent in the south-east. Further blustery showers on the 17th merged to give longer spells of rain in the afternoon. Rain cleared most places by the morning of the 18th to leave behind scattered showers, heavy at times and of hail in places, with strong north-westerly winds.
19th to 26th:
It was a fresh bright day on the 19th with scattered showers, heavy in places. Another bright day followed for the 20th, with any showers light and more isolated. Showers were restricted to the west on the 21st, other areas remaining dry and bright. Mainly dry on the 22nd with the west mainly cloudy and eastern areas seeing the best of any sunshine. After a dry and bright start on the 23rd, a band of rain spread from the west during the afternoon. The 24th was mainly dry with sunny spells but remained cool in a westerly wind. There were isolated showers in the south-east during the morning of the 25th but a dry and sunny afternoon followed. The 26th was dry with sunny spells.
27th to 31st:
Rain spread from the west on the 27th, becoming persistent and heavy in the afternoon before clearing to leave showers. The 28th saw frequent blustery showers. Cold north-westerly winds brought further showers on the 29th, some heavy and accompanied by hail and thunder. It was mainly dry on the 30th until rain arrived in the evening. The 31st gave some sunshine, but there were also scattered showers, some heavy.