More than 200 flood alerts are in place across the UK on Sunday, as heavy rain mixed with melting snow marks the latest weather battle.
There have been more reports of flooding in south Wales overnight, weather experts said, as the downpours replace almost two weeks of snow.
Norfolk Police have reported flooding caused by melting snow and ice, which has closed a number of roads in the area.
Wales, central England, and the south west will be the worst-hit areas where at least one inch of rain is expected to have fallen by mid-morning, while the rest of the UK can expect around half-an-inch.
Rising temperatures of up to 12C have sparked a rapid thaw of the snow and ice which has built up in the recent cold snap, further exasperating potential flooding problems.
The Environment Agency has issued 30 flood warnings, urging people to take immediate action against predicted flooding, in the Midlands, the west of England, central England and Wales.
A further 218 flood warnings are in place across England, Scotland and Wales affecting all but the east of England and north of Scotland.
Chris Burton, a forecaster for MeteoGroup, the weather division of the Press Association, said: "The rain started falling overnight in the west and will move east across all areas of the UK, with at least half-an-inch falling in most areas.
"The worst affected areas will be Wales and the south west.
"We have had some reports of flooding in south Wales which have had heavy downpours.
"There is also likely to have been some in north England and the Midlands where there is a large amount of snow melting.
"But from mid-morning the rain should lift and it should remain largely dry, with some scattered showers.
"Winds of up to 60mph will also cross the UK today."
He added that the heavy rain will return on Monday along with the risk of flooding as the surface water and river levels build up ahead of an unsettled week.
Around 18 buildings flooded in various locations across Wales on Friday night, including two houses in Solva, Pembrokeshire and two in Dolgellau, North Wales.
An EA spokesman said: "Emergency teams from the Environment Agency will be out in force throughout the weekend shoring up defences, monitoring river levels and clearing blockages from watercourses."
The latest heavy snow storms on Friday night into Saturday left hundreds of people stranded for hours on motorways in the north of England.
The M6 was blocked in both directions between junctions 25 and 27 in Lancashire when a sudden burst of more than a foot of snow brought drivers to a standstill from around 8.30pm, the Highways Agency said.
Many became stuck along the stretch of motorway between Wigan and Standish after struggling to make it up inclines in the treacherous conditions, while a number of accidents including jack-knifed lorries also blocked lanes.
Mountain rescue workers were drafted in to help with rescue operations and check on the condition of drivers stranded by the snow.
A diabetic man was taken to Royal Blackburn Hospital after falling ill, while an ambulance taking a female patient to Royal Preston Hospital had to be dug out of the snow by Bowland Pennine Mountain Rescue team.
Phil O'Brien, team leader of Bowland Pennine Mountain Rescue, said: "It was potentially a very serious situation. The Highways Agency managed to get people moving at about 4.30 to 5am (on Saturday).
"There were hundreds of cars stuck but most people seemed in good spirits."
Some of the stranded drivers passed the time having snowball fights and building snowmen, while others abandoned their cars completely.
Conservative MP for Morecambe and Lunesdale David Morris, who was stuck on the south-bound carriageway, said:
"We've ground to a halt on both sides. Nothing is really moving.
"But the emergency services have been fantastic and are doing the best for us, and everyone is in good spirits.
"I've just seen a snowball fight and the man next door to me has built a snowman on top of his car roof - it's very surreal."
Prime Minister David Cameron took to Twitter to express his sympathy for those caught up in the snow.
A family had to be evacuated when the gable end of their house collapsed, apparently under the weight of fresh snow in Barnsley, South Yorkshire.
Meanwhile, hundreds of swimmers braved the freezing weather yesterday to take part in the UK Cold Water Championships at Tooting Bec Lido, south London.
The death toll during the recent cold snap, which is in double figures, is thought to have risen further as it was feared a man in his 30s or 40s might have frozen to death after going missing in woodland.
His body was found on Thursday night after four friends went to Newmarket police station in Suffolk reporting that he had not been seen for four days. The men had been searching for him and found him dead in a wooded area.
The death is being treated as unexplained but one theory is he died in the freezing temperatures.
A father died on Thursday when his car skidded into a river just before his wife's vehicle also plunged into the icy water.
BBC employee David Cox, 42, was taking his 11-year-old daughter Tess to school when their Toyota Aygo left the path and crashed into the River Wye in Derbyshire.
Moments behind them in a separate car, a Toyota Rav 4, was his wife Ruth, 39, and son Ioan, nine.
Mrs Cox also lost control as she drove along the bridlepath near the Monsal Trail, north of the A6.
The children and their mother managed to get out of the cars and safely to shore but Mr Cox was unable to escape.
Neighbours tried to save him but it is believed he was trapped for around 40 minutes. He died in hospital.
Other casualties of the cold spell include postman John Bircham, 57, who collapsed soon after he was towed out of a snowdrift in Dulverton, Somerset, last Saturday, and Bernadette Lee, 25, who was found collapsed in the snow in Deal, Kent, last Sunday following a night out.