Thunderstorms may develop on Sunday bringing torrential rain and lightning, with possible flooding and disruption to travel.
Spells of rain are expected to affect many areas at times from Sunday afternoon and into Monday, moving north-northeastward and perhaps turning thundery at times in some places.
Scattered heavy showers and thunderstorms may also develop between bands of rain, particularly on Monday afternoon.
Where thunderstorms do develop, 20 to 30 mm rain may fall locally in an hour, and close to 40 mm of rain may fall in two or three hours.
Deputy Chief Meteorologist at the Met Office, Laura Ellam, said: “High pressure will bring a brief spell of warmer, drier and sunnier weather this weekend. However, as low pressure re-establishes later on Sunday, we’re going to see a return to the heavy rain and thunderstorms we’ve seen so far this June. Rather than the recent cooler conditions, it’s going to feel much warmer and humid.
“Whilst it will feel warmer for everyone in the UK next week, parts of southern and eastern England will see the hottest weather with temperatures here into the high 20s Celsius, possibly exceeding 30 Celsius at the peak of the heat by Wednesday or Thursday.
“With this hot and humid weather there is the potential for severe thunderstorms developing, bringing the risk of torrential downpours, hail, flash flooding and gusty winds.
“We are carefully monitoring the situation and will update any National Severe Weather Warnings as confidence in where the greatest impacts from the thunderstorms and heavy rain increases.
“As such we are urging people to keep a close eye on the latest forecasts and advice on the Met Office website, app and social media channels.”