Dull and wet start, but spells of warm dry sunny weather expected towards mid-July
Updated 20th June 2017 - Covering the period 26th June - 18th July
Mean temperatures will be 0.5 to 1.0C above the long-term normal over much of the country, but 1.5C above in eastern Scotland and parts of north-east England.
Rainfall will tend to be much above normal early in the forecast period but falling below normal by the second week of July. Overall, the wet start to the period will tend to result in above average rainfall (though not exceptionally so) for much of the Midlands and southern England, but rather below normal in northern and eastern Scotland, with near to slightly below normal rainfall elsewhere.
Sunshine totals will start off low and will recover as the period progresses. For most of the country sunshine will come out close to average overall, but with excesses likely in eastern Scotland and north-east England.
Monday 26th June to Sunday 2nd July
This will be a very wet and unsettled week over the British Isles with low pressure dominating the weather almost throughout, especially during the middle part of the week.
Rain will clear eastwards early on the 26th, though the rain belt may hang around in East Anglia and the south-east for most of the day. Following behind will be a window of bright weather with scattered showers, but on the 27th, following a bright start, cloudy, wet and breezy weather will spread from the west. Temperatures will generally be a little above the seasonal norm.
Between the 28th and 30th, low pressure will be very close to or on top of the British Isles. There will be some slow-moving rain belts around which will bring spells of overcast wet weather.
Temperatures will tend to be near normal by day and above normal by night in the east, but cooler than average by day in the west. Away from the rain belts, there will be occasional sunny intervals but a fair amount of cloud, and some slow-moving thundery downpours. Temperatures will tend to be below normal by day but above normal by night.
A change to a more mobile westerly type is expected on the 1st and 2nd, which will mean less in the way of heavy rain, but it will be generally cloudy with daytime temperatures a little below normal.
Mean temperatures will be about 1C below the 1981-2010 long-term normal in Northern Ireland and some Irish Sea coasts, but about 1C above in eastern and northern Scotland. For much of the country, temperatures will be below normal by day but above normal by night.
Rainfall totals will be near or rather below normal in north-west Scotland but above normal elsewhere, possibly exceptionally so in parts of England.
Sunshine totals will be near normal in the north and west of Scotland, but elsewhere it will be somewhat cloudier than normal with Wales and western England in particular seeing a considerable shortage of sunshine.
Monday 3rd July to Sunday 9th July
This week will start off with changeable westerlies, but with an increasing tendency for ridges of high pressure to move eastwards across southern parts of the UK, bringing intervals of warm and dry weather with variable cloud cover. There is a significant chance of the weather turning more anticyclonic generally near the end of the week promising more widespread warmer and sunnier conditions, as a more sustained ridge of high pressure is expected to spread from the Azores to cover a significant chunk of Europe.
As a result, mean temperatures will tend to be a little above normal over much of the UK, typically by about 1C, but with very close to average temperatures near west-facing coasts and in Northern Ireland. Rainfall and sunshine totals are generally expected to be close to normal for most regions but with a tendency for above average sunshine in the south and east of England and below average sunshine in western Scotland.
Monday 10th July to Tuesday 18th July
This period will be more anticyclonic than usual, with a fine spell expected, most likely around the 10th-15th, with plenty of warm dry sunny weather for much of the UK, but probably turning cooler and cloudier near the end of the period. Temperatures will mostly be above normal, with an above average chance of heatwaves with temperatures into the high 20s and low 30s Celsius, especially around midmonth, although confidence over the extent of any hot spells is low at this range. Consequently, this period is expected to be warmer, drier and sunnier than average for much of the UK, with western areas favoured for the largest positive sunshine anomalies due to a below average incidence of westerly winds. The positive temperature anomaly will tend to be around 2 to 3C.