UK Weather Shifts from Warm Start to Wetter, Windier Week
A warm start to the week will give way to wetter and windier conditions as the jet stream strengthens, bringing low-pressure systems and cooler
Changeable autumn weather will continue across the UK this week, with a warm start making way for spells of wetter and windier conditions. A strengthening jet stream will drive deeper low-pressure systems later in the week, with the potential for minor disruption by the weekend.
Monday will see a short-lived burst of warmth and sunshine before temperatures drop. Higher pressure may build again towards the end of the month, but the prospects for a late-September heatwave remain uncertain Weather.
A Strengthening Jet Stream Drives Change
The jet stream, a ribbon of fast-moving air about six miles above the ground, dictates much of the UK's weather. Early in the week, this jet stream will be weak and loop north of the country. This pattern allows higher pressure to develop, bringing a warm south-westerly airflow.
Later, the jet stream will shift to a faster, straighter, and more southerly path towards the UK. This change will allow lower pressure to form, introducing periods of rain and brisk winds. Temperatures will consequently fall from their Monday peak.
Temperatures Drop Through the Week
Monday is forecast to be the warmest day. Air arriving from the south-west will make it feel warm and rather humid, even though many areas will stay fairly cloudy with some rain near western coasts and hills. Temperatures are expected to climb above 20C widely.
Where sunshine breaks through, particularly in central and southern England, temperatures could reach as high as 26C. By Thursday, however, winds will turn westerly or north-westerly, ushering in a fresher and cooler air mass.
Temperatures by Thursday will show a marked cooldown compared to the start of the week.
| Region | Expected Temperature Range (Thursday) |
|---|---|
| Scotland & Northern Ireland | 14 to 16C |
| England & Wales | 17 to 20C |
Uncertain Outlook for Late September
Forecast models suggest areas of high pressure may gain more influence during the final week of September. This could lead to longer dry spells and a return to above-average daytime temperatures. The exact degree of any warming will depend on where the high pressure settles relative to the UK.
Long-range forecasting is uncertain, and details are subject to change. BBC Weather currently states there is "nothing to indicate that a heatwave is on the cards." As autumn advances, high pressure overhead could instead lead to some chilly mornings due to the longer nights. The forecast ends on the note that high pressure building at the end of the month remains a possibility, but the heatwave potential is unclear.
