Northerly and then easterly winds during late May, turning wet for most into June
Updated 16th May 2017 - Covering the period 22nd May - 13th June
It will be cooler than average in eastern England and eastern coastal parts of Scotland, typically by 0.5 to 1.0C, but warmer than average (again by 0.5 to 1.0C) in Northern Ireland and in south-west Scotland. Elsewhere temperature will generally be within 0.5C of normal.
Rainfall will mostly be below normal until early June but it will then become wet for most. For the period as a whole, it will be much drier than normal in northern Scotland and generally dry also for south-west Scotland and Northern Ireland, but most of England and Wales will have near average rainfall and it will be wetter than average in the south.
Sunshine totals will be above normal in western Scotland and in Northern Ireland, but below normal in the east of Scotland and central, southern and eastern England, with near to slightly below average sunshine elsewhere.
Monday 22nd May to Sunday 28th May
Northerly winds will blow more frequently than usual during this week, resulting in rather cool weather with a west-east split, though the winds are expected to turn mainly easterly by the end of the week with high pressure building across the north of the UK.
Between the 22nd and 24th, low pressure out in the North Sea and high pressure in the mid-North Atlantic will bring persistent northerly winds over the British Isles. It will be dry and mostly sunny in Northern Ireland and western Scotland, but cloudier further south and east, with either scattered showers or longer outbreaks of rain, the latter most likely for north-east England, Lincolnshire and East Anglia.
Temperatures will be below normal for the time of year except in south-west Scotland, with highs mostly between 11 and 14C, but up to 17C in south-west Scotland.
Although there is some uncertainty over the specifics during the second half of this week, the general theme will be for the winds to veer north-easterly and then easterly. It will become warm and sunny in western Scotland and in Northern Ireland, but cloud cover will remain extensive in eastern Britain, especially near North Sea coasts, and some light rain and drizzle is expected in eastern parts of England.
Mean temperatures will be 1 to 2C below the 1981-2010 long-term average in central and eastern parts of England and in eastern Scotland, but up to 1C above in Northern Ireland and south-west Scotland, and near to slightly below average elsewhere.
Rainfall will be below normal except in eastern England, with some counties bordering the North Sea seeing above average rainfall.
Sunshine totals will be above normal in northern and western Scotland and in Northern Ireland, but well below normal in eastern England and rather below in eastern Scotland. Most of Wales and western England will have near to slightly above average sunshine.
Monday 29th May to Sunday 4th June
Easterly winds will remain more frequent than usual during this period. Pressure will fall in the North Atlantic, so it will begin to turn more unsettled from the west into early June. A fine spell is expected in the north and west, especially early in the period, but the easterly winds will continue to bring issues with low cloud into eastern Britain. With the winds tending to turn east to south-easterly rather than north-easterly, however, sunshine amounts will increase in East Anglia and the south-east. Some thundery outbreaks are possible in the south late in the period with the possibility of some storms moving up from the near-continent.
Mean temperatures will tend to be above normal during this period, typically by about 2C, but will be below normal in coastal parts of eastern Scotland and north-east England. It will be drier than average for most parts of the UK, but with close to or rather above average rainfall for Northern Ireland and southern and south-western parts of England. Sunshine totals will be below normal in eastern Scotland and north-eastern England, especially in counties bordering the North Sea, but well above normal in western Scotland and north-west England.
Monday 5th June May to Tuesday 13th June
This period will be rather wet and cloudy for most of the UK with North Atlantic depressions tracking further south than usual, and easterly winds blowing more frequently than usual in the north. The Atlantic trough will tend to drift eastwards over to Britain as the period progresses. Temperatures will be above normal for much of the country early on the period with southerly winds blowing more frequently than usual and an above average incidence of thunder, but later in the period the emphasis is expected to be more on frontal rainfall, with temperatures below normal by day.
Overall, temperatures during this period will be close to or just above the long-term normal, but any positive anomaly will be down to high overnight minima. Rainfall will generally be above normal except in the north and west of Scotland, but it will be dry in north-west Scotland. Sunshine totals will follow a similar pattern, below normal for most (mainly due to a dull second half of the period; the warmer thundery start may well produce close to average sunshine) but above normal in the north and west of Scotland.