The cold snap, which has brought sub-zero temperatures to parts of the UK, looks set to worsen.
Snow is causing havoc on the roads
The Met Office has issued severe weather warnings for eastern England and eastern Scotland.
Snow in Scotland, particularly on high ground, has forced the closure of more than 30 schools in Aberdeenshire.
Across south-east England and East Anglia heavy snowfall is forecast to hit throughout the night - with more snow expected later in the week.
Up to 10cm is possible over high ground - particularly in the Pennines and Cheviots - with treacherous conditions expected on Wednesday and Thursday.
A Met Office spokesman said "temperatures will be below zero in the worst affected areas", making driving dangerous due to icy roads.
He added: "Forecasters are keenly watching developments through this week, with a real possibility of some significant snow in the south."
Heavy snow will move south across the whole of Northern Ireland with Counties Antrim, Down and Armagh hit hardest.
People across the rest of southern England and the Midlands are being warned to expect snow.
The Highways Agency warned drivers to be extra vigilant and to delay journeys if bad weather persists.
Some children are making the most of the snow storms
The snow showers claimed the life of a 20 year-old man in Cramlington, Northumberland, in a sledging accident.
Mark Young, of Ashington, Northumberland, suffered neck and back injuries in the accident at around 2100 GMT on Sunday night.
He was taken to Wansbeck General Hospital but was later pronounced dead.
The late winter cold snap is blamed on high pressures over Scandinavia and northern Europe and low pressures to the west of the UK, which have caused temperatures to plunge.
It has come as a shock to those who assumed the worst of the winter was over, particularly as last month was the warmest January for 15 years.
There have already been several minor incidents on East Anglia's roads and Suffolk police said they were "absolutely amazed" at the irresponsibility of drivers.
The RAC has reported difficulties with the weather in Nottinghamshire, Kent and North Yorkshire.
In northern England snow showers will be heaviest to the east of the A1 at first, before extending westwards.
Rob Nicholls, head of street services for Newcastle city council, said the city would be on "red alert" for the next few days due to forecasts that the freezing conditions are set to continue.
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