The Met Office has issued a red weather warning as Storm Dennis batters the UK.
The warning - the highest threat level - states that deadly floodwater poses a threat to life, with parts of South Wales set to be heaviest hit.
Homes have been evacuated after the River Taff burst its banks, and forecasters warned locals could face several days of misery.
A further five amber and four yellow warnings are in place, with the whole of the UK affected.
"It's quite an extreme move but we have seen widespread falls across the whole region," forecaster Greg Dewhurst said.
Severe flood warning were issued for the Scottish Borders and for the River Neath in South Wales.
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Prolonged, heavy rain is expected to continue until mid-morning, easing slowly into the middle of the day.
Up to 140mm is expected over higher ground in South Wales.
At 7am today there were 198 flood warnings - meaning immediate action is required - and 326 flood alerts warning people to be prepared, covering an area from Scotland's River Tweed to the rivers of west Cornwall.
There will be a danger to life from fast flowing or deep floodwater and extensive flooding to homes and businesses is likely.
Mr Dewhurst said "heavy rain and strong winds" would continue across large parts of the UK on Sunday.
"South Wales will see a lot of rain fall before Dennis moves north later to Scotland and Northern Ireland," he stated.
Travellers are advised to check for traffic alerts such as road closures, bus and train service delays and cancellations.
It comes after Storm Dennis' winds peaked at 87mph on Saturday and six inches of rainfall fell.
British Army troops have been deployed to support flood relief supports in West Yorkshire, as well as Scotland.
Defence Secretary Ben Wallace said: "Our armed forces are always ready to support local authorities and communities whenever they need it.
"The rapid response of the Army today will help with provision of flood relief to local communities in West Yorkshire."
More than 230 easyJet flights in and out of the UK on Saturday were cancelled, while several sporting fixtures were also called off due to the weather.
Two bodies were pulled from rough seas on Saturday, before the worst of the storm hit.
One man was found following a huge search operation off Margate after an early-morning distress call, while another was found at Herne Bay.
