Winds and torrential rain left one person dead and forced hundreds from their homes - as David Cameron promised the Government would "ensure everything is being done to help".
The Prime Minister's comments came as the Environment Agency revealed more than 800 homes have been flooded, with thousands of motorists rescued from water-logged roads.
A woman was killed when she was crushed by a tree as wild winds whipped southern England, bringing the week's weather-related death toll to two.
And on Sunday night, forecasters have warned the worse may still be to come, with further rainfall and 60mph winds expected overnight, with experts warning people the conditions pose a "serious threat to life".
Rainfall is estimated to be around 15mm across the spine of Britain on Monday, less than the 30mm of rain in pockets of the West Country, but meteorologists said it would offer little respite to weary homeowners keen to begin the clean-up.
Cameron wrote on Twitter:
Although Sunday afternoon saw a temporary respite, the Environment Agency has continued to issue warnings, with over 500 alerts now in place.
One severe flood warning - the highest alert possible - remains in place for the River Cober in Helston, Cornwall. At one point this weekend, four were in place.
More than 500 alerts have now been issued, including nearly 230 flood warnings - the second strongest alert - and confined largely to the Midlands as bands of rain which brought sorrow and destruction to the South West moved northwards.
A 21-year-old woman became the second victim to die as a result of this week's weather after she was killed in Western Way, Exeter after becoming trapped under a fallen spruce tree which injured two others.
It follows the death of a man on Thursday, who died when his car became wedged under a bridge near a ford in Rectory Fields, Chew Stoke, Somerset.
There were serious problems across Britain and Wales, with Yorkshire, Warwickshire and Wiltshire badly affected today.
Environment Minister Richard Benyon met with people in Malmesbury where three feet (90cm) of water was reported in some parts of the Wiltshire town.
He described the clear-up work as "heroic", adding: "While many houses have been flooded, some haven't because of the efforts of these people.
"The Government's job, first of all is to make sure people are as prepared as possible with a changing climate ... for these extremes of weather. Secondly, we've got to continue building flood defences."
Many people took to social networking sites to express their fears and frustration at weather conditions and preparations made in advance.
Both the RAC and AA breakdown services reported surges in flood-related call-outs as roads and highways across the country were closed due to perilous standing water.
But that has not deterred many motorists from taking their chances, incurring the wrath of one emergency worker who hit out at risk-takers.
Nathan Hudson, general manager of West Midlands Ambulance Service, appealed for members of the public to stop endangering their and rescue workers' lives.
"People who attempt to pass through flooded roads are not only putting their own lives at risk, but also the lives of the emergency services staff who have to rescue them.
"A little bit of common sense from the public will ensure that no one's life is put in any unnecessary danger."
National Rail said the severe weather is disrupting services across the South West.
Trains were cancelled between Exeter St Davids and Yeovil Junction because of a landslip at Honiton and flooding near Axminster in Devon, and replacement buses were cancelled because of severe flooding on local roads. The route is expected to reopen tomorrow, subject to no further damage.
Property owners across the country are tonight preparing for another deluge - and forecasters have warned the situation could get worse before it gets better.
Tom Tobler, forecaster with MeteoGroup - the weather division of the Press Association - said more rainfall is expected overnight.
He said: "There may only be 10-15mm of rain overnight, but that would enough to worsen the situation for some people who have already experienced some flooding.
"The worst rainfall could be in north Wales, with 20-30mm of rain.
"I don't think the rainfall will be as significant as last night, but there will be strong winds and sharp frosts as the week goes on."
He said temperatures in Scotland could plunge to freezing by Tuesday, and in the rest of England by Wednesday evening.
Cameron's comments came two years after flash floods caused havoc and widespread disruption to mid-Cornwall, and resulted in both the Prime Minister and the Prince of Wales embarking on separate visits to the worst-hit towns and villages to pledge their support.
Stephen Gilbert, the Liberal Democrat MP for St Austell and Newquay, said the Government needed to act in ensuring insurance companies were able to provide home and business owners with affordable cover.
He said: "Yet again I call on the Government to reach an agreement with insurers that will keep flood insurance available and affordable.
"The last two days should be a wake-up call for a Government that needs to grip this issue and do so quickly.
"We know that flash flooding is increasing because of climate change and there's now little we can do to stop it, but the Government must act to make sure people aren't left without insurance when the worst does happen."
Emergency services tonight urged motorists to take extra precautions when tackling roads tomorrow morning, following the anticipated heavy rainfall.
Gloucestershire Police said they anticipate disruption on some of the county's roads during the early morning rush hour, as a band of heavy rainfall moves from Cornwall towards the Midlands.
A spokesman said: "It's thought that the main routes in and out of Tewkesbury will see flooding, potentially making them impassable to vehicles, especially on Gander Lane, Ashchurch Road near to the A38 junction and Church Street.
"Drivers are also advised that the road between Drybrook and Ross at Hawthorns remains closed due to a landslip.
"Motorists are urged to stay safe by reducing their speed, driving carefully and considerately and to not drive into floodwater as you cannot anticipate how deep it is."