Monthly weather forecast for the UK
Updated 26th July - Covering 2nd - 24th August 2021
Cool and changeable, though not particularly wet, warming up towards mid-August
Mean temperatures are expected to be between 0 and 0.5C above the 1981-2010 long-term normal over much of the country, thus very close to the normal. Warm weather is expected in mid to late August but this will be largely offset by a cool start to the month.
Rainfall totals are not expected to deviate far from the long-term normal during this period, but they will tend to be slightly above normal overall, probably by just 10 to 20% in most regions. Near to slightly below average rainfall is more likely for south-western Britain.
Sunshine totals are also expected to be close to normal for most of the UK, with a cloudy start to the period offset by a relatively sunny end, but in much of Wales and south-west England they will tend to be a little below normal.
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Week 2: Monday 2nd August - Sunday 8th August
The 2nd and 3rd are expected to have a slack north-westerly flow over the British Isles, bringing fairly cool and cloudy weather with some scattered showers, though for Northern Ireland and south-western Britain it will probably be dry with some sunshine. From the 4th, more depressions will move in from the North Atlantic, giving Britain a generally west to north-westerly type. One or two short-lived ridges of high pressure will move eastwards across the south, but generally it will be unsettled with low pressure quite dominant to the north and north-east. There will be some rain belts moving from west to east at times, though probably with only low rainfall amounts associated with them in the south and south-east. In between there will be some brighter, showery weather. Temperatures will tend to be close to or just below normal.
Mean temperatures are thus forecast to be about 1C below the 1981-2010 long-term normal in most parts of the UK, although south-western Britain may end up close to normal.
Rainfall totals are most likely to be near normal in most parts of the UK, as rainfall amounts are not generally expected to be excessive despite the unsettled weather mid to late week. East Anglia is most likely to have above average rainfall overall.
Sunshine amounts will be below normal in most regions, but in some western parts of the UK, especially Northern Ireland and western Scotland, they may be close to or just above normal.
Week 3: Monday 9th August - Sunday 15th August
The unsettled west to north-westerly type is expected to continue for much of this week, but with a growing tendency for a north-south split in the weather towards the end of the week, with high pressure ridging into the south more frequently, and the prevailing wind direction switching to a west to south-westerly.
Temperatures will probably be close to normal during this week, with cool temperatures early in the week but then turning warmer as the winds turn more south-westerly and high pressure moves into the south more frequently. Rainfall totals will thus most likely be near or a little above normal in most parts of the UK, but it is again not expected to be outstandingly wet, with an emphasis on light to moderate rain from fronts moving from west to east, and some scattered showers in between the rain belts. Sunshine will probably be close to normal for most parts of the country, with sunshine amounts generally picking up late in the week, but they will be below normal in many western areas due to the generally westerly regime.
Rest of month: Monday 16th August - Tuesday 24th August
There is plenty of uncertainty over this period, but there is some chance of the high pressure to the south moving further north and east, especially early in the period, bringing a spell of hot and sunny weather to many parts of the UK, but it will probably be a case of one or two short-lived interludes rather than an extended anticyclonic spell. Overall, temperatures are expected to be above average during this period as a result, most likely by around 2C for most parts of the UK although in Scotland and Northern Ireland positive anomalies of nearer 1C are likely. Confidence in rainfall totals is low, as there are likely to be some unsettled, possibly thundery, interludes during this period. Sunshine totals will most likely be rather above normal for most parts of the UK.
Monthly weather forecast
The month ahead forecast is written by Ian Simpson and is updated every Monday.
