Freezing weather will grip Britain for weeks to come, forecasters have warned - with rain, sleet and snow expected across the country.
Some of the worst widespread early snow for 17 years has seen much of the country disrupted and police in affected areas are urging people to stay indoors.
Severe weather warnings have been in place, with Scotland and North East England experiencing the worst of the weather, and snowfalls of up to 40cm in some areas.
There was also snow across parts of Wales, the West Midlands and Cornwall and temperatures across the country struggled to rise above zero even in the major cities.
Northumbria Police urged motorists to stay off the roads and advised people to dress in warm clothing.
Forecaster Tom Tobler of MeteoGroup said: "The temperature throughout the day has struggled to get above zero in many areas.
"It will be a similar situation tomorrow, staying very cold, with Scotland seeing the majority of the snow showers. But there may be snow in some western areas as well.
"Overnight it will be very cold, well below zero everywhere, going down to minus 7C quite widely. The cold weather will stay during the week with a brisk easterly wind developing which will make it feel even colder and which might bring more snow showers."
He said there could be a mix of rain, sleet and snow later in the week, adding: "People should be bracing themselves for more cold weather for the working week and beyond."
Two people were injured in a four-vehicle pile-up on the M1 near Sheffield, where an inch of snow was lying on minor roads. The crash, involving a lorry and three cars, happened shortly before 8am and the Yorkshire Air Ambulance was called to the scene.
Flights at some airports were delayed - including at Jersey Airport where lightning hit the radar system overnight. There were also runway closures at airports including Luton, Newcastle and Inverness.
The unusual weather has been caused by high pressure over Greenland and low pressure in the Baltic, forcing cold winds from the north east across Europe.