Britain will face more downpours before the skies clear for a “subtropical swell” of 24C heat, forecasters say.
Bright sunshine and widespread temperatures above 20C will offer Brits one last taste of summer at home this week before the autumn sets in.
The mercury is expected to soar in parts of the UK from Tuesday afternoon, with glorious sunshine across much of England from Wednesday, according to the Met Office.
The warmer air could even rival temperatures in Málaga, but not before yet more wet and dreary weather.
Heavy rain is expected to lash the north-west of England and Scotland on Tuesday, with the drizzle moving south throughout the day to western coasts.
South east England will stay drier with cloud cover.
The latest Met Office forecast says: “Rain in the northwest, heavy at first, edging southwards. Fog patches clearing the south then brighter, though cloud increasing.
“Windy in the north. Feeling warmer across parts of the east.
“Some clear spells over Scotland otherwise cloudy with rain and drizzle for western coasts and hills through the night. A mild night for all.”
On Tuesday, temperatures across much of England will hit 20C, with southeastern parts enjoying up to 24C – unusually hot for September and on a par with many Spanish tourist hotspots.
The Met Office outlook for Tuesday adds: “Some sunny spells for east Scotland and northeast England otherwise mostly cloudy with light rain for western coasts and hills. Heavier rain in the north later. Warm in any brightness.”
The mercury could also climb to 22C on Wednesday as the southern half of the country basks under clear sunny skies with low winds.
The sunny spell will offer teachers and pupils back at school some respite for outdoor socially-distanced learning, while commuters making their return to the office will have something to anticipate on the lunch break.
Temperatures are expected to tail off towards the more seasonal mid-teens in the latter half of the week, but forecasters say the wind and rain will continue to stay away for most areas.