Yesterday's brief thaw left a lot of surface water - which the AA and RAC warned would freeze overnight to turn roads into ice rinks.
The London Weather Centre said: "The temperature will struggle to get above freezing point, but with the wind chill factor it will feel like minus 10C or minus 12C."
The motoring organisations said the thaw had cleared most snow-blocked roads yesterday. Only minor roads in Scotland and the North-east remained closed, and conditions in Peak District passes were difficult, the RAC said.
The AA was predicting a blizzard of calls this morning, as cars left idle over the weekend failed to start.
An AA spokesman said: "We are expecting a large number of breakdowns because we have got the worst weather for cars' electrical systems - very cold and wet."
Drivers should take extra care in the icy conditions, it added. "The advice is to do everything slowly - keep speeds down, don't stamp on the brakes, don't jerk the steering wheel. Leave extra time for your journey and keep a good gap between you and the car in front."
After a night of temperatures well below zero, snow flurries were forecast to move in from the east coast and work their way westwards across the country, but no significant snowfall was expected, the London Weather Centre said.
Water companies dealt with an epidemic of burst pipes across the country over the weekend, the Water Services Association said.Reuse content