Drivers have been warned of icy conditions and increased likelihood of breakdowns as freezing conditions continue to sweep across the country.
Temperatures have fallen to -10C in parts of Scotland and -7C in southern England, causing difficulties for millions of motorists and commuters.
Experts predict that temperatures in the South will fall further overnight on Tuesday, to -8C or -9C, as an unusually large high-pressure system dominates the UK weather. That is more than 10C below seasonal temperature norms of a degree or two above freezing for this time of year.
Brendan Jones, a forecaster at MeteoGroup UK, the weather division of the Press Association, said: "The lowest temperature so far is -10C at Aboyne in north east Scotland.
"Across large parts of England and Wales we will see -5 or -6C, while in the south they will go to -7C. But tomorrow in the South is going to be colder than tonight, with temperatures falling to -8C or -9C."
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