The week-long early snowfalls and freezing temperatures - the earliest since 1993 - are set to worsen. Thousands of homes have been without power and hundreds of schools are shut.
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The Met Office has severe weather warnings in place for Scotland, the eastern areas of Northern Ireland, the east coast of England down through the North East, Yorkshire and Humber, the East Midlands and Cornwall.
The forecasters now predict the bitter winds will increase and the snow will spread to more areas including London and the South East.
Scotland and the North East have, so far, been worst hit by snow, with more than 40cm falling in some areas.
All schools in Dundee, Perth and Kinross, West Lothian and Shetland were closed this morning. Some 200 schools are closed in Tyne and Wear, Northumberland and County Durham.
Thousands of homes across Tayside and Central Scotland have been affected by power cuts.
Martin Bristow, who is a teacher, lives in the village of Murthly north of Perth
Conditions are horrendous and we would urge caution. Central Scotland Police spokesman
He told Channel 4 News he was without power from late on Sunday night until lunchtime on Monday: "It was about 11.30pm and basically the power went off as we were about to watch a DVD.
"We got a flash about half an hour later but then it went back out.
"We have tropical fish which is difficult because obviously you have to keep the fish at a certain temperature.
"I've got a coal-burning fire so I kept that running overnight to keep the tank warm."
Motorists, who became stranded in Tayside on Sunday night, were put up in Perth Grammar school.
Andy Nicol, from Linlithgow got stuck trying to get from Dundee back to West Lothian: "When we got to Perth we realised there was no way we were getting home so the police directed us to Perth Grammar school where we spent the night.
"It was as good as it could be. There was tea, coffee, blankets, there were beds and we slept in the gym hall so they couldn't have done much more.
"I've never seen the weather this bad - the A92 was horrendous, it was terrible, it was really slow..you just had to be patient. It was just stop, start, stop, start."
Overnight blizzard conditions and jack-knifed lorries forced the closure of the A9 between Dunblane and Perth - one of the busiest roads in Scotland.
A spokesman for Central Scotland Police warned of dangerous conditions on the roads throughout the rest of the force area saying: "Conditions are horrendous and we would urge caution."
In North Tyneside district nurses battled through the snow to treat patients unable to leave their homes, reports Channel 4 News North of England correspondent, Nick Martin.
District nurse Jill Thompson drove on the icy roads to treat an elderly woman with severe diabetes.
"We've had to dig our cars out of the car park and drive through the snow to see some patients but the need medical help," she said. "For some people there is simply no choice."
This year marks the 150th anniversary of the formation of the district nursing service.
69 year old Monica Robinson has severe diabetes and urgently needed insulin. The district nurse had no choice but to travel to get there.
"If we couldn't make it we would have to call the police. She would die if she didn't get this insulin," she explained.
It is a visit which takes only five minutes, but could save the patient's life.
"It's so reassuring to know that the nurses will come whatever be weather," says Mrs Robinson. Can you imagine if no-one came out to see us."
Further south, the M62 between junction 34 and junction 38 in West Yorkshire was described by authorities as "hazardous", while one of the main routes into the centre of Sheffield - the Parkway - was said to be "treacherous".
One lane of the eastbound M4 at the Severn Crossing was closed for a while as a precaution after ice started to form on the bridge.
Record low temperatures have already been recorded in some parts of Wales and Northern Ireland. Llysdinam, near Llandrindod Wells in Wales, registered minus 18C yesterday. Today it is minus 12.9C, while Lough Fea in Northern Ireland sank to minus 9.2C. In the West Country North Dartmoor was minus 7.9C this morning.
The Local Government Association says councils have increased stockpiles of road salt and grit after the snowfalls earlier this year. Spokesman David Sparks said they were well prepared, but warned: "You cannot control or battle with the weather if it is unprecedented, you can only mitigate the effects."
Twitter users have been adding their experiences of the early wintry weather to a UK snow map.