Plunging thermometers will push the mercury close to -5C (23F) overnight on Saturday with the risk of frosts on Sunday morning.
Bookies are hedging their bets on the first flakes of the year, with Ladbrokes offering 5/1 from 20/1 on a flurry anywhere in the UK before midnight on Sunday.
Piers Corbyn, director of WeatherAction, said things will take a bitter turn from Saturday especially in Scotland.
He said: “There is a chance we could see the first wintry showers of the season between Saturday and Monday.
Leon Brown, forecaster for The Weather Channel UK, said: “It is looking rather cool for the rest of the week with temperatures 2 to 4C below normal.
Thanks to Andrew Stranglen and Marcus Adrian for this link