Parts of the UK could see temperatures reach as high as 22C (71.6F) this week, according to the Met Office.
Forecasters say the cool temperatures seen this weekend will creep up to much milder conditions for all throughout next week, peaking on Wednesday.
Some places could end up about 10C warmer by midweek, with London potentially exceeding 20C (68F).
Peak temperatures are expected particularly in East Anglia and the Home Counties, which the Met Office says could reach around 22C.
Most regions are projected to have temperatures in the mid-teens on Wednesday, Thursday and Friday.
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"Temperatures are going to rise gradually, peaking probably on Wednesday in eastern areas, and we might well see in some spots 20C, and 22C is not out of question, probably in eastern England - so East Anglia down towards the South East," said Met meteorologist Tom Morgan.
"But it will be much milder compared to now for everyone."
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"It's possible we could exceed 20C in London but the peak temperatures might well be up towards the Home Counties and up to Cambridgeshire," he added.
He warned the warmer weather will be short-lived, giving way to wet and windy conditions by next weekend.
That could be the case particularly in the North West, including Scotland and Northern Ireland, but possibly less so in the South East.
In the West and Wales, that wet weather could come by midweek, he said.
(c) Sky News 2024: UK weather: Temperatures to rise across country this week - with some areas potentially su
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