Rainfall totals will be below normal in all parts of the UK, and especially so in Wales and the western side of England, in spite of a wet end to the forecast period. In north-east Scotland, rainfall totals will only be slightly below normal.
Sunshine will be above normal in most parts of the UK but below normal in north-east Scotland, and in general most of Scotland, plus the eastern side of England, will have close to average sunshine. Sunshine will be above average in Northern Ireland, south-west Scotland, Wales, and central and western England.
Monday 21st August to Sunday 27th August
This period will see a strong ridge of high pressure from the Azores move over to southern Britain, especially around midweek, bringing dry sunny weather, but mainly westerly winds on the northern flank of the high will bring cloudier weather to the north.
A weakening rain belt will head south-eastwards across the country on the 21st with brighter, showery weather following behind with a brisk west to north-westerly flow. It will be breezy and will be a little cooler than average for the time of year. North-westerly winds will be lighter on the 22nd, which will be a bright day for most, dry and sunny in the south-west but with scattered showers in most other parts of the UK, the showers heaviest and most frequent in the north-east. It will remain on the cool side.
High pressure will ridge into the southern half of Britain on the 23rd and this ridge will stick around until at least the 25th, bringing dry sunny weather with mean temperatures close to or just above the seasonal norm. With clear skies and light winds, this means a combination of warm days and chilly nights. The dry sunny weather is also expected to affect Northern Ireland, but in Scotland it will generally be cloudier and breezier, especially in the north, with a little light rain at times. Some of this cloud may also feed down the eastern side of England. Nonetheless, even in Scotland, especially in the east and south, there will be some dry bright interludes as well. Confidence is lower on the 26th and 27th when we may see more unsettled conditions try to push in from the north-west but relatively high pressure will hold on in the south.
Mean maximum temperatures will be 1 to 2C above the 1981-2010 long-term average over many parts of England, Wales and Northern Ireland, but near normal in northern Scotland. Mean minimum temperatures will be near normal in most parts of the UK and perhaps a little below in the south. As a result, mean temperatures during this period will typically be between 0 and 1C above the normal with most regions about 0.5C above.
Rainfall totals will be below normal in all parts of the UK, though only slightly below in north-east Scotland, and well below normal in Wales and south-west England.
Sunshine will be a little below normal in north-east Scotland but generally above normal elsewhere, particularly in south-western Britain and also in Northern Ireland.
Monday 28th August to Sunday 3rd September
This week will see high pressure remain close by to the south, with mainly westerly and north-westerly winds on the northern flank of the high. Thus, it will tend to be cloudier for Scotland and some of this cloud may again spread down the eastern side of England at times, but in the west and south it will be mainly dry and sunny. The high pressure will be less dominant than in the previous week so it is probable that there will be some disturbances with frontal systems bringing cloud and light rain on occasion, but the south will probably see only small amounts of rain, if any.
Heatwaves are unlikely as the winds will mostly be blowing from the north-western quarter of the compass, so mean temperatures will typically be close to or just above normal, again typically within a degree of the normal. Rainfall will again be below normal, but less exceptionally so than during the previous week. Sunshine totals will be above normal in Wales and the west and south of England, but with other regions tending to have close to average sunshine.
Monday 4th September to Tuesday 12th September
This period will start off relatively quiet but is expected to turn more unsettled with a dominant westerly flow developing over the UK, and by the end of the period we may see some quite deep depressions moving close to the country bringing wet and windy weather. Temperatures will rise above the seasonal norm early in the period but will then fall close to normal when the westerlies get underway. With a transition occurring in the weather it will tend to be drier and sunnier than normal early in the period for most, but late in the period it will turn wet, with sunshine totals below normal in the west but near normal in the east. Overall rainfall totals will be close to normal over much of the UK with sunshine above normal in the east and near normal in the west.