UK Set for Late September Warm Spell Before Atlantic Winds and Rain Take Over

Britain is set to enjoy a burst of unseasonably warm weather at the start of the working week, as southerly winds draw milder air up from the continent and Iberia. Forecasters say a large area of low pressure sitting out in the Atlantic is responsible for pulling these south to south-easterly winds across the country, delivering a final taste of summer warmth before more typically autumnal conditions settle in. Tuesday is expected to be the warmest day of the spell, after which temperatures should slide back towards the seasonal average for late September.

The warmth will not arrive evenly, however. Monday morning is likely to feel distinctly chilly for many, with clear skies overnight allowing temperatures to dip. Forecasters are warning that fog patches could develop in places, potentially causing tricky conditions for the morning commute. Once any fog lifts, most areas should see a brighter day, with high pressure bringing sunny intervals and only a scattering of showers. South-east England may catch some rain during the afternoon and evening, though this is far from certain. Daytime highs on Monday are expected to reach the mid to high teens, with parts of the south touching 20C.

The real shift comes on Tuesday, when a strengthening southerly breeze ushers in noticeably warmer conditions. Scotland and Northern Ireland are forecast to reach the high teens, while England and Wales could see temperatures ranging between 20C and 26C. It is a remarkable contrast for a country that has just experienced its hottest summer on record, and it continues a pattern of unusual warmth that has characterised much of September for large parts of the UK.

That warmth will not last, though. Rain is expected to push into Northern Ireland during Tuesday afternoon before slowly tracking eastwards through the evening and overnight. The downpours may turn persistent and occasionally heavy, accompanied by strong winds and gales in exposed coastal and hilly areas. Areas further east may hold on to drier, brighter conditions for longer, with the rain not expected to arrive until Wednesday, and possibly lingering overnight in some places.

Behind that band of rain, the weather returns to a more familiar mix of sunny spells and scattered showers, with western regions staying windy through Wednesday. By Thursday, high pressure is expected to build back in, bringing calmer, drier conditions. Friday could see the north-west become the focal point for any remaining showers. Forecasters caution that details can shift, and people are advised to check short-term local forecasts as the week progresses.

The coming unsettled spell highlights a stark divide that has defined September across the UK. While Scotland and western areas have been battered by repeated Atlantic weather systems bringing rain and strong winds, much of central, southern and eastern England has stayed largely dry and sunny. That split has produced dramatically different rainfall totals, with some drought-affected parts of England receiving very little rain at all.

By contrast, parts of north-west Scotland have been extremely wet. Some locations, including Kirkwall and Prestwick, have already recorded nearly one and a half times their average September rainfall. At Achnagart in the Highlands, rain has fallen every single day for the past 27 days, an extraordinary run that underscores just how persistent the wet weather has been in the north-west.

Elsewhere, parts of Northern Ireland and Wales have received roughly their normal September rainfall, while north-east England has recorded some of the lowest totals so far this month. The disparity reflects the broader north-west to south-east split that has dominated the UK's weather patterns in recent weeks.

The dry conditions in central, southern and eastern England matter because many of those areas remain affected by drought. Recent research has suggested that at least seven months of relentless rain would be needed to fully end drought conditions in the worst-hit regions, meaning this week's expected rain is unlikely to provide any meaningful relief there. For those communities, the approaching low pressure system may deliver far less rain than it will to the north and west.

The broader context is a summer that broke temperature records across the UK, followed by a September that has continued to run warm for many. While nights are now longer than days following the autumn equinox, the strength of the September sun can still deliver comfortable daytime warmth when skies clear. That combination of cooler nights and mild days is typical of early autumn, but the upcoming spike in temperatures is more pronounced than usual.

Looking ahead, the pattern favours a return to more changeable, autumnal weather, with the Atlantic low dictating conditions for much of the country. Wind, rain and gales will affect exposed western coasts and hills, while eastern and south-eastern regions may escape the worst of the downpours. The week therefore offers a little something for everyone: a final warm flourish, followed by the familiar sound of rain against the window and leaves blowing down the street.