The Met Office has issued its most severe flooding alert for the South West as heavy rain continues to inundate many parts of Britain.
The red warning covers areas around Plymouth and Exeter, as the South West region bears the brunt of downpours.
The alert urges residents in the region to "take action" as 100mm of rain, about four inches, is forecast to be dumped in the next 24 hours.
And nearly 320,000 people have been warned not to attend the British Grand Prix at the Silverstone race track in Northamptonshire after rain left thousands stranded in traffic jams near the site.
More than 170 flood alerts have been issued - meaning flooding is possible - in the South East, Wales and Scotland.
There are nearly 70 flood warnings in place throughout the UK - the North East has 50 warnings in place while the North West, the Midlands and East Anglia are on flood precautions.
"We would urge people to remain on alert for flooding, especially in Devon, Cornwall and Somerset," said Craig Woolhouse, of the Environment Agency.
Many parts of the country received more than half the average rainfall for July on Friday and the Met Office says there will be no let-up on Saturday.
The south Pennines and north Midlands, including the areas around Manchester, Sheffield, North Derbyshire and Nottinghamshire, which have been among the worst areas hit by the latest floods, remain at risk of flooding over the weekend.
About 100 properties have already been flooded around the country in downpours that have closed roads and caused landslips which led to delays on some major rail routes.
Six people had to be rescued from a caravan park in North Yorkshire on Friday after the site was left under 2ft of water.
It was a soaking day at Silverstone on Friday when a deluge of up to 40mm of rain fell in just 12 hours, leaving some car parks unusable.
As well as warning fans to stay away from Saturday's qualifying session, race organisers even told F1 supremo Bernie Ecclestone not to bother turning up.
The circuit's managing director, Richard Phillips, said: "We dissuaded him from coming in. He was coming in by road, but he could have been five hours."
Mr Phillips issued an "unreserved apology" to fans, adding the incident almost reduced him to tears.
He said the financial hit is likely to run into seven figures, which for this season will potentially turn a profit into a loss.
"We've been in emergency meetings every two hours today with the police, highways agencies, county council, emergency planning to try and resolve the issues," said Mr Phillips, who said refunds would be offered to those who failed to get into the venue.
"It's going to cost us a lot of money. I honestly don't know the figure, but it could be a lot more than hundreds of thousands (of pounds).
"Right now we're trying to get ourselves into a situation to get in as many people as we can from a position of devastation."