Torrential rain is causing disruption as a month's rain falls in parts of the UK within one day.
The number of flood warnings - meaning flooding is expected - has reached more than 60 in England, and more than 170 flood alerts are in place in the UK.
The Environment Agency said 94 homes had been flooded in England and Wales, as forecasters warn of more heavy rain.
The Met Office has issued a red warning for severe weather in parts of the South West from midnight.
A red alert is its highest, and warns people to take action, rather than the lower alerts warning people be alert or be prepared.
The town of Darwen in Lancashire, which was evacuated last month when rivers burst their banks, is among 65 places in the North East, the North West, the South West, the Midlands and the Anglian region of England, that are subject to a flood warning.
Meanwhile, a live flood warning system has gone online to help people track the areas in imminent danger.
And 20,000 Grand Prix fans have been warned not to attend the Silverstone race track on Saturday, as rain left thousands stranded in traffic jams near the site.
In other developments:
- Prince Charles has visited flood-hit Hebden Bridge, in West Yorkshire
- Heavy rain caused flash flooding and long delays across Oxfordshire's roads
- A police command centre has been set up in Sheffield over fears of flooding, while an extra 150 South Yorkshire Police officers are working on Friday night
- Six holiday-makers were rescued from a flooded caravan park in North Yorkshire
- Fourteen tourists, including a baby, were rescued after flash flooding on the Isle of Mull, on the west coast of Scotland, on Thursday
- Flooding has hit several parts of Wales, affecting roads and homes
- Network Rail is reporting a number of line closures and delays, including waits of up to 90 minutes for trains departing Kings Cross after a landslip at Grantham blocked the line between Peterborough and Doncaster
- Heavy rainfall has caused problems across parts of Nottinghamshire and Lincolnshire
- Businesses in Lancashire were evacuated over fears a wall could collapse due to heavy rain
- Parts of Derbyshire have been hit by flash flooding, with pupils from one school sent home
- In County Durham, heavy rain caused problems for events and businesses
- There has been severe flooding in parts of County Down in Northern Ireland
- Six people were rescued from their cars as heavy rain caused flooding in parts of Staffordshire
- Some sporting fixtures, including cricket, horse racing and tennis, have been affected, and the MFest music festival was cancelled
Some parts have received more than half the average rainfall for July in just one day, forecasters said. The average rainfall for this month is 60mm.
Overnight the worst affected area is expected to be south-west England, which has already seen heavy rain, with 40mm falling in just 30 minutes in Somerset earlier.
Forecasters said a further 80mm is expected to fall across the South West later and it is not expected to ease off until Saturday afternoon.
The Met Office's red warning centres on south-west Devon and east Cornwall.
EA officials are visiting campsites in these areas to warn of the severe weather conditions.
Meanwhile, in Northern Ireland there is no flood warning system but the Met Office has issued a yellow warning - urging people to be aware - for its south-eastern tip.
Craig Woolhouse, EA head of flood incident management, urged people to remain "on alert" for flooding as the situation could "escalate quickly".
He urged people to stay away from flood water.
The EA has opened incident rooms and has teams out checking on flood defences and clearing any blockages to reduce risks as much as possible.
The latest flood warnings follow the UK's wettest June since records began in 1910, according to provisional Met Office figures.
BBC Weather's Chris Fawkes said that, for the past three months, the UK had found itself underneath an accelerating part of the 6-mile high Jet Stream - a fast wind blowing around the planet.
An accelerating Jet Stream causes air to rise upwards through the atmosphere and creates low pressure centres and a greater likelihood of rain, he said.