A month's rain has fallen in just a few hours in some areas as the heatwave broke in a series of heavy thunderstorms.
Pershore in Worcestershire recorded 56mm (2.2 inches) of rain in a three-hour period, more than the area's 50mm average total for the whole of July, the Met Office said.
Monks Wood in Cambridgeshire saw 33mm (1.3 inches) in the 12 hours to 1pm while nearby Brampton recorded 48mm (1.9 inches) in the same period.
The Met Office had weather alerts in place for heavy rain across much of the UK and more serious warnings for parts of northern England and the East Midlands in the evening.
These areas could see downpours of up to 60mm (2.4 inches) falling in less than three hours, which could cause localised flooding and disruption. There is also a risk of "large" hail.
There are also weather alerts for heavy rain in place for Scotland and eastern England on Wednesday, with the risk of 20mm to 40mm (0.8 inches to 1.6 inches) of rain falling within in a few hours in some places and possible flash flooding.
The storms follow scorching temperatures, which peaked at 33.5C in London on Monday - the hottest day since July 20 2006.
An area of high pressure has been hanging over the UK for a few weeks, creating settled, very hot conditions, but now air has pushed in from the Atlantic and met the humid conditions, causing strong and violent storms, forecasters said.
Gareth Harvey, forecaster at Meteogroup, the weather division of the Press Association, said: "In the last couple of hours another cluster of heavy showers and thunderstorms have been developing through central parts of England and the Midlands. That could continue to develop and start to affect north-west areas of England. They're gradually going to be moving eastwards."
He said that by the end of Tuesday night places would be starting to become dry, but storms would still be hanging on to some parts of Scotland, and far eastern England, with one or two heavy showers in those areas on Wednesday morning. By later, however, another showery band of rain will start to move in from the west.