Most of the country is set for a wet and cloudy festive period with heavy snow coming two weeks early, the Meteorological Office says.
A white Christmas is expected in the Scottish Highlands.
At the same time, temperatures will hover above freezing in northern Scotland and lower levels there may see some snow on Christmas night, as cool winds push in from the north-west and blow across the whole UK.
After this band of rain, conditions will be drier in the south and east of England with blustering winds across the North West, Wales and Northern Ireland.
Snow blankets the UK, with more wintry weather to come - in pictures
“It’s going to be a cloudy and wet Christmas weekend for some of the UK and any wintry showers are most likely to be confined to the far north-west of Scotland," said Met Office spokesman Stephen Dixon.
“A white Christmas, which according to the Met Office is defined by a single snowflake falling anywhere in the UK on Christmas Day, is most likely in the north-west of Scotland later on in the day on Sunday, with some snow moving in from the north-west as part of a cooler pool of air.
"And some snow could even be seen in the north-west of the UK at lower levels overnight on Christmas Day and into Boxing Day.
“What we’re looking at for Christmas Eve is staying mainly dry for southern and eastern parts but areas to the north-west will see some showers and some longer spells of rain for a time, including some heavy rain for a short time, and some snow falling over the high ground of Scotland.
“Some breezy conditions as well on Christmas Eve, some gusty winds especially in the north and west of the UK.
"That scene continues into Christmas Day with unsettled weather in charge of the UK regime at the moment.”
Snow blankets the UK - video
For the weekend in general, Mr Dixon said the country would face typical weather for this time of year, with “a mild, more unsettled pattern in charge”.
“Strong winds and rain continue for north and western areas in particular," he said.
"Further south won’t be immune to the occasional shower but the drier weather is expected in central and eastern parts of England."