Sub-zero temperatures in the past two days do not signal the start of a big winter freeze, forecasters say.
Bookmakers had slashed the odds of a white Christmas for 2004
Temperatures plummeted to -7C (19F) on Friday night, and Saturday will see freezing rain in the west of Britain and temperatures as low as -4C (25F).
But Sunday marks the start of a spring-like warm spell, with temperatures up to 13C (55F), BBC weather staff say.
Bookmakers have been taken by surprise - many had cut their odds on a white Christmas following the cold snap.
Ladbrokes bookmakers slashed their white Christmas odds from 4/1 to 7/2 on Friday and William Hill followed suit.
"The odds suggest there is a much better chance
of snow this year than there was in 2003," said Ladbrokes spokesman Warren Lush.
He said one gambler had put £5,000 on London seeing snow on Christmas Day at odds of 5/1.
But a spokeswoman at the BBC Weather Centre said she was surprised at the flurry of seasonal betting.
"Saturday is the last of the winter weather before it turns spring-like. The weather will be warm for the foreseeable future," she said.
Over the past two days Britain has seen some of the coldest weather of the year.
Snow fell in Birmingham, parts of the East Midlands, Milton Keynes, Cambridgeshire, Essex and Northern Ireland on Thursday night.
Up to 6cm of snow has also fallen across the Highlands and Aberdeenshire in Scotland, with snow showers across north Wales continuing on Saturday.
Shap Fell in Cumbria was the coldest place in Britain on Friday night, with a recorded temperature of -7C (19F).
The AA Roadwatch has advised drivers to be careful of icy patches, while the Highways Agency said drivers should check for up-to-date information on weather and
road conditions before they set off.
The BBC Weather Centre warned of rain hitting freezing ground causing treacherous conditions on many roads throughout Wales, western Scotland and the west of England.
But a south-westerly air flow on Sunday is expected to bring warmer temperatures to most parts of the UK.