Much of the UK including North West England is expected to be covered with a blanket of snow that in some places could be 6in (15cm) deep.
But it will disappear almost as soon as it has arrived, heralding drier, warmer and sunnier weather for the rest of the week, forecasters predict.
The Met Office has issued severe weather warnings for much of Scotland and northern England, advising people to be aware of snow fall.
Snow will move into western Scotland and pass eastwards throughout the day across most parts of the UK, although west Wales, south west England and coastal parts of the South will see rain instead.
But later it will begin to clear and turn increasingly to rain and drizzle in western areas as milder air begins to move in.
Sally Webb, a forecaster with MeteoGroup, the weather division of the Press Association, said: “We will see up to 2cm (1in) across the South East throughout the day, 2cm to 5cm (1in to 2in) quite widely, and over higher ground and in the North up to 8cm (3in), or 10cm (4in) across higher ground.”
“Overnight it will turn to patchy rain and drizzle across the UK, before a band of heavy rain moves in during the early hours. It will also be windy today, especially across northern Scotland.”