A woman is missing after the country was lashed by heavy rain, floods and snow that have brought widespread disruption.
Police spent the morning using a sniffer dog to search for the woman after floodwater crashed through her home in Looe, Cornwall.
Devon and Cornwall Police say Susan Norman, who is in her 60s, has not been seen or heard of since 6pm yesterday.
Neighbours said they heard "windows popping" at the three-storey property under the pressure of a torrent of surface water which had been washed down the road behind the building, which is split into three flats.
Fire and Rescue search teams have been unable to carry out a thorough search of the building as it is too dangerous.
Devon and Cornwall Police duty inspector Graham Claybourn said: "The property and adjoining properties were evacuated this morning, everybody was accounted for.
"However, one lady has not been accounted for. She lives in the ground flat."
It came as up to 40cm (16ins) of snow was expected over high ground in the Midlands, north and east Wales and northwest England, with 10-15cm (four to six ins) in lower lying areas.
Up to 30cm (12ins) of snow was predicted for Northern Ireland across the hills of counties Antrim and Down, with high winds leading to blizzard conditions.
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The snow was expected to continue into Saturday with the Met Office saying another 5-10cm (4-6ins) was possible in some areas of central Britain.
Two amber warnings for snow have been issued, meaning that the public in some places should be prepared for "severe disruption, particularly to transport and power supplies".
The bad weather resulted in the Sellafield nuclear reprocessing plant in Cumbria being shut down.
A spokesman said: "In response to the current and predicted adverse weather conditions on and around the Sellafield site, as a precaution, a site incident has been declared and the plants on the site have been moved to a controlled, safe, shutdown state.
"There is no reason to believe that there will be any off-site nuclear, environmental or conventional safety issues associated with the incident."
In Northern Ireland, more than 48,000 homes and businesses were left without power and around 60 schools were closed.
George Best City Airport closed its runway for a while but later announced it had reopened and flights from Belfast International Airport were disrupted.
Northern Ireland's World Cup qualifying match against Russia at Windsor Park in Belfast has been called off.
In West Yorkshire, Leeds Bradford International Airport has suspended all flights due to "adverse weather conditions".
The airport has told passengers: "We advise you contact your airline or tour operator and check the status of your flight before arriving at the airport."
Among the main roads affected in the region are the A1(M) between the end of the M1 and the A62 junction, between Leeds and York, where snow has closed a lane, the M62 near Brighouse, where another lane has been closed due to the weather and the A66 across the Pennines which has been closed in both directions between the A685 and the A1.
Police in Cumbria have established a multi-agency 'Gold Group' to co-ordinate its response to a number of incidents.
A spokeswoman said police had received about 20 calls throughout the morning for assistance following multiple reports of road traffic collisions, impassable roads from trees falling, road signs blowing over and heavy snowfall.
Despite a series of accidents on the region's road network, North Wales Police said all main routes were passable but urged drivers to take care.
In the West Midlands, nearly 230 schools shut their doors to pupils, with many reporting burst pipes and frozen heating systems.
In Staffordshire, 170 closed their doors, but there was also disruption in Walsall, Dudley and Wolverhampton.
Nearly 200 schools closed across North Wales and scores more closed across Yorkshire, Derbyshire, Nottinghamshire, Lancashire and Cumbria. Schools across Greater Manchester appeared largely unaffected.
In Scotland, police advised supporters travelling to tonight's Scotland V Wales World Cup qualifier at Hampden Park, Glasgow, that due to the adverse weather, Queens Park Recreational Ground, off Queens Drive, would be closed.
They said that as a result, there would be nowhere to park vehicles within the ground for the game and advised people to make other travel arrangements.
Yesterday and last night there was flooding across the South West, with Penzance, Newlyn, Porthleven, Stithians, Bridge, Mevagissey, Colebrook and Holbeam among the towns hit and early reports suggesting around 10 properties had flooded.
At one point, there were 96 flood warnings in place across the country, with south west England the worst affected.
Fifteen flood warnings , meaning flooding is expected, and 40 flood alerts, where flooding is possible, are now in place across the south west. Another 36 flood alerts applied to East Anglia, the Midlands, the south east and Wales.
Sgt Dave Opara, based in Plymouth, said: "There has been a considerable amount of rainfall across the force area."
Cornwall opened its dedicated control centre to deal with the volume of calls about flooding.
Newlyn, in the southwest of the county, was reported to be the worst affected area.
Sky's weather presenter Nazaneen Ghaffar said: "The snow will turn to sleety rain over north Wales and the north Midlands for a time, reverting to snow again later. Southern Britain and south-east Ireland meanwhile will see more heavy rain, bringing local flooding in the west where another 5cm, (2ins) are possible.
"There'll be more snow tonight, from around the M4 up into central Scotland and across the north of Ireland, while southern counties will have yet more rain. Saturday will see snow over central parts slowly fading, but there'll be a raw wind and it will stay near freezing away from the south-west.
"The average temperature for the month so far, combining day and night, has been around 3C, well below the long term average of 6C. It’s highly unlikely to be record breaking (the coldest March on record was in 1962, at 1.9C), but it could well be the coldest for over 25 years."
Environment Agency spokesperson Pete Fox said the public can sign up for flood warnings and check the latest information on the Environment Agency's website , or follow us on Twitter at @EnvAgency.
Darron Burness, head of the AA's Special Operations Response Team , said: "It's going to be a real witch's brew of driving wind, rain and snow, which will inevitably cause disruption on the roads.
"Drivers should be well prepared as even short journeys can quickly turn bad."
The Local Government Association said council gritting and ploughing teams would be out in force to try to ensure main roads remained passable.
Meanwhile, the Duchess of Cambridge had to battle through the weather in order to reach her appointment of the day - a Scout camp in the snow-bound Lake District.
Wrapped up against the biting cold, five-months pregnant Kate arrived at the Tower activity centre near Newby Bridge, near Windermere, wearing a fleece, green parka-style jacket, and wearing wellies and a friendship knot.
Kate knelt in the snow to show them how to make fire from sparks using flints and cotton wool, cheering along after one youngster - after several attempts, managed to create a flame.
Also, Battersea Dogs & Cats Home is calling on Londoners to donate the items to help the animals in its care during March's unexpected cold snap.