Updated 22nd August
Covering the period 29th August - 20th September
Hot beginning, otherwise quite dry with temperatures slightly above normal, turning cooler into early September
Mean temperatures will be very close to the 1981-2010 average, but around 0.5C below in most western areas (especially Northern Ireland) and around 0.5C above in eastern England.
Rainfall will be a little above normal in south Wales and south-west England but below normal in most other regions, especially eastern Scotland and north-east England.
Sunshine totals will be somewhat above normal in south-east Scotland and north-east England, but a little below normal in south-western Britain, and generally slightly above normal elsewhere.
Monday 29th August - Sunday 4th September
This week will start off relatively quiet under a ridge of high pressure, but will turn progressively more changeable and windy from the west.
A ridge of high pressure will bring dry sunny conditions to most parts of the country on the 29th and 30th, but a trough close to the south-east will bring thundery outbreaks to parts of southern England, and the north and west of Scotland will be cloudier with some light rain or drizzle.
On the 31st, a depression will move eastwards from the North Atlantic bringing a belt of rain south-eastwards across the country, followed by brighter showery weather, although rainfall amounts will be small in the south. A ridge of high pressure will build from the south behind this weather system, bringing dry and bright weather to most parts of the country on the 1st and 2nd. However, lows will come back in from the west on the 3rd and 4th bringing belts of rain, giving more significant rainfall totals in the south, and it will turn windy in the west.
Temperatures, relative to the 1981-2010 long-term average, will be close to normal in Northern Ireland but about 1C above average in most other parts of the country.
Rainfall totals are expected to be close to or above normal in western Scotland, Northern Ireland and also in south Wales and south-west England, but it will be drier than normal in most central and eastern parts of England.
Sunshine totals will be below normal in Northern Ireland, while elsewhere they will be close to normal in the west and above normal in the east.
Monday 5th September - Sunday 11th September
This period will have below average pressure over Scandinavia, bringing unsettled and fairly cool conditions with rain belts moving across the country at frequent intervals. Early in the period there will be frequent cloudy wet weather with frontal systems especially affecting southern and western areas, and brighter showery conditions frequent over Scotland. Late in the period, high pressure will come close to south-western areas and the weather will turn showery generally, with temperatures falling a little below normal.
Temperatures will be up to 1C below the 1981-2010 average in most western parts of the UK, but fractionally above in East Anglia and the south-east.
It will be wetter than average over most of England and Wales, especially the south of England, but with close to average rainfall for north Wales, Northern Ireland, Scotland and north-west England. Sunshine totals will be above normal over most of Scotland, especially the west of Scotland, but it will be cloudier than average over central and southern and eastern England and south Wales.
Rest of the month
Monday 12th September - Tuesday 20th September
The prevailing signals are for above average pressure over the British Isles, so it is probable that high pressure will move in from the west bringing much quieter weather. It is expected to be colder than average early in the period with some cool nights in particular, then warming up later in the period as the high pressure moves slowly eastwards. For the period as a whole, temperatures will be very close to average. Much of the UK, especially the west, will be drier than average. Sunshine totals could vary either way from average in the east, depending on the precise positioning of the anticyclone, but are most likely to be close to or slightly above normal. In the west, it is expected to be sunnier than average.