Torrential rain, thunder and lightning is blighting the first weekend of the school holidays, as thousands set off across the UK for their summer break.
The heavy downpours have already caused flash-flooding in the South East and the Midlands, with more expected as the rain spreads north and west.
In just four hours on Saturday evening Market Bosworth in Leicestershire endured 61mm of rain and many other areas saw between 20mm and 30mm, with similar amounts forecast For Sunday. This compares with an average rainfall of around 80mm for the whole month of July, weather experts said.
The Met Office has increased its weather warning level to "amber", the second of three levels, urging residents in the Midlands and north of England to be prepared for storms likely to cause surface water flooding and disruption.
The Environment Agency has also issued 32 flood alerts in the same areas, and two more serious flood warnings near Rochdale and Sheffield as river levels rise.
But forecaster Tom Tobler, from MeteoGroup, the weather division of the Press Association, said there is a chance of being hit by heavy downpours almost anywhere in the UK.
He said: "The torrential rain and thunderstorms will move into north England and into Scotland, as well as across to the South West and South Wales. Between 20mm and 30mm could fall, some of it on top of areas which might have already seen showers, so there is a continued risk of flash-flooding.
"But you could catch a heavy shower pretty much anywhere in England and Wales, but the South East should remain mainly dry and up to 25C."
Eight "flood alert" warnings have been put in place across much of Scotland, particularly the east and south of the country. The Scottish Environment Protection Agency (Sepa) said rain could be "intense" in some areas but would ease off as the day went on.
The areas affected stretched from Dumfries and Galloway in the south-west across to the Borders and north through Edinburgh, central areas, Perthshire, Angus and Aberdeenshire.