Thunderstorms are expected on Wednesday evening and Thursday night, which will briefly stop the hot weather in London.
He warned that in some areas there may be disruptions, especially during travel.
Weather forecaster Richard Miles told The Standard: “There is a warning of thunderstorms that we expect to see tonight and tonight.
“There will be quite a bit of rain, lightning and maybe hail.”
However, Thursday will return dry weather with temperatures up to mid-20 degrees.
Mr Miles continued: “If the downpours pass tomorrow morning, Thursday looks pretty good again.
“Then on Friday you could see the shower, but mostly well. There may be a thunderstorm again, but it doesn’t look like heavy rain for a long time. “
Mr Miles said the weekend would be “mostly dry and a little windy”.
“It’s getting colder,” he added. “But it means that by the weekend the temperature will return to normal. It will not be cold, except for heavy rains, it will be mostly good and dry. “
This comes after the UK recorded it the hottest day of the year on Tuesday in Heathrow the temperature of mercury reached 27.5 degrees.
London was hot, with temperatures exceeding the previous high for the year, which was 23.6 degrees Celsius in Faversham, Kent, on 6 May.