The Met Office has issued a yellow warning for ice and snow affecting London and the south east of England this weekend, and an amber warning for Sunday.
The weather forecasting service said there was a risk of possible travel delays due to wintry conditions today and tomorrow.
Two to five cm of snow is likely in large parts of the UK, while 10-20 cm is possible for some locations, mainly in northern Scotland, Northern Ireland, north Wales and perhaps the northwest Midlands
"During Friday, increasingly frequent snow showers already affecting parts of Scotland, Northern Ireland and northern England will extend across many other northern and western parts of the UK," said the Met Office.
"Icy surfaces are also likely to be an additional hazard, especially overnight. The heaviest and most frequent snow showers will progressively become confined to northeast Scotland during Saturday."
Meanwhile, the Met Office advised: "A spell of heavy snow is likely over parts of Wales, the Midlands and parts of Northern England on Sunday. Road, rail and air travel delays are likely, as well as stranding of vehicles and public transport cancellations. There is a good chance that some rural communities could become cut off."
The Met Office warning comes as Storm Caroline nears the UK.