The weather in May

http://www.theguardian.com/uk-news/2015/jun/07/may-weather-temperatures-rainfall-sunshine

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Last month ended the recent sequence of dry spring months in England, with rainfall generally above normal. Wales and the northern half of the UK suffered an unsettled and wet month, as low pressure systems moved across. Winds generally blew from a westerly quarter, and monthly averaged wind speeds were above normal for May. With below average sea temperatures over the North Atlantic, it was not surprisingly a chilly month in northern and western parts of the British Isles, especially around windward coasts. Further south and east, warming of the land in fairly modest amounts of sunshine gave temperatures closer to normal.

Daytime Temperatures

The average daily Central England Temperature was 11.0C, just 0.7C below the average for 1981-2010. Western parts of Scotland averaged 1.6C below normal in a month that rounded off a slow start to spring here. Northern Ireland and north-west England were each around 1C below average. Mean maximum temperature during May ranged from 9.5C at Lerwick (Shetland) to 17.4C at Gravesend (Kent). The highest temperature of the month was 22.7C at St James’s Park (Central London) on 11 May. The lowest overnight temperature was –5.6C at Tulloch Bridge (Inverness-shire), on the morning of 1 May.

Rainfall

Rainfall over England and Wales during May averaged 83mm, which is 130% of the average for the standard reference period 1981-2010. The equivalent figures for Scotland were 116mm and 147% of the normal amount, and for Northern Ireland 123mm and 170%. In the last 100 years over England and Wales, 78 Mays were drier, while 22 were wetter. Monthly totals at routinely-available sites ranged from a total of 151mm at Lake Vrynwy (Powys) to just 40mm locally in the London area. Scattered locations on eastern coasts of England and Scotland received just under the monthly average, a sign of a westerly month. The heaviest daily fall was 55mm at Tyndrum (Stirling) on 3 May.

Sunshine

After an exceptionally sunny April, May was on the dull side, especially in the north and west, where low pressure areas and associated bands of cloud and rain passed most frequently. Sunshine averaged over England and Wales during May was 173 hours which is 92% of the 1981-2010 mean. The equivalent figures for Scotland were 157 hours and 91%, and for Northern Ireland 131 hours and just 70%. Largest total in the UK was 186 hours at St Athan (Vale of Glamorgan) and the smallest was 101 hours at Lerwick (Shetland).