Updated 15th September - Covering 22nd Sept - 14th Oct 2025
Mean temperatures are expected to be not far from normal overall, probably about 0.5C above the 1991-2020 long-term normal in the west and nearer 1C above in the east and especially south-east, in spite of a rather cool start to the forecast period. The prediction of mostly above average values is influenced by the persistence of the marine heatwave around the British Isles, as our air masses tend to be heavily modified by the surrounding seas.
Rainfall totals for the period as a whole are likely to end up near normal due to dry weather early in the period being offset by wet weather into October, but there is a substantial chance of the period as a whole ending up drier than average in western Scotland.
Sunshine totals will probably end up generally above normal in north-western Britain due to sunny weather in Week 2, while the east and south of England will probably see near or slightly below average sunshine.
This week will start with a northerly blast on the Monday, bringing below-average temperatures for the time of year, and some showers for eastern counties, although the west will be predominantly sunny and dry. Given that recent weather has tended to be warmer than average, it may especially feel cooler than what we’ve been used to. After the northerly runs out of steam, high pressure will build, but there is some uncertainty over how north the high pressure will end up.
There is about 30% chance of low pressure remaining close to the south-east, bringing north-easterly winds and some rain and showers into eastern areas, especially eastern England, off the North Sea, and dry sunny weather for the north-west. Alternatively, the high has potential to build on top of the country, bringing dry sunny weather to many areas, although eastern England will still be more prone to cloudier weather, and perhaps a scattering of light showers, coming in off the North Sea in that scenario. In either case it looks probable that high pressure will become dominant towards the end of the week, but potentially again with easterly winds and cloudier weather for eastern England, while north-western Britain looks set to be dry and sunny.
Traditionally this is quite a cool setup normally at this time of year, but this will be offset to some extent by the marine heatwave around the British Isles, with sea surface temperatures well above the long-term average. Thus, mean temperatures are forecast to be 0 to 1C below the 1991-2020 long-term normal in most western areas, where there is potential for nights to be cool under clear skies, while near North Sea coasts it will generally be up to 1C warmer than normal, with the winds coming in off the comparatively warm North Sea.
Rainfall totals are forecast to be below normal for most of the country, but there is uncertainty over rainfall amounts in the east of England, especially East Anglia and the south-east, where there is about a 1 in 3 chance of it ending up wetter than average because of low pressure potentially being slow to clear the south-east. Confidence is high in considerably drier than average weather in Scotland (except near the east coast), Northern Ireland and north-west England. Sunshine totals are forecast to be generally below normal in eastern England and possibly near the east coast of Scotland, but mostly above normal elsewhere, especially in Northern Ireland and western Scotland.There is a weakening signal for high pressure during this week, most likely with the high pressure slipping south-eastwards early in the week allowing some warmer weather to take hold, with more sunshine in eastern England than during the previous week, but cloudier and wetter weather heading into the west of Scotland. During the latter part of the week, it is likely to turn more unsettled from the west generally, although confidence is relatively low: the high pressure could end up more stubborn than is currently being modelled. Overall, the most likely outcome is near average rainfall and sunshine for most of the country, with temperatures a degree or two above the long-term normal.
This period is most likely to see unsettled, low pressure dominated weather for most of the time, with predominantly westerly and south-westerly winds, although as noted regarding Week 3, confidence in this is relatively low, so it is subject to change depending on whether the high pressure to the east and north-east in Week 3 proves stubborn or readily moves away eastwards. Overall the most likely outcome is above average rainfall, with sunshine below average in the west and near or rather above normal in the east, especially the north-east. Temperatures are likely to be near to slightly above normal overall, with the south-east most likely to see above-average temperatures.
Monthly weather forecast
The month ahead forecast is written by Ian Simpson and is updated every Monday.
