Temperatures plummeted towards sub-zero overnight as Arctic air descended on the UK, with snow possible in some parts of the country today.
Snow was spotted on hills in Cumbria, while Inverness, Newcastle, and York were among the cities where it fell as low as 1C (33F) in the early hours. It also dropped that low as far south as Southampton, according to the Met Office.
Check the weather forecast where you are
It's expected to get even colder throughout this week during the first cold snap of the year, as a spell of above-average temperatures comes to a brutal end.
Sky News weather presenter Jo Wheeler said the sudden change would feel "shocking" to some.
Multiple yellow weather warnings for snow and ice have been issued by the Met Office for parts of Scotland and northern England until Thursday, while the UK Health Security Agency has issued an amber cold health alert for the North East, North West and Yorkshire and the Humber until Friday.
A yellow cold health alert affects the rest of England, with the cold air having made its way over from Siberia.
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While it's set to be wet in Scotland, Northern Ireland, and northern and western parts of England and Wales today, the Met Office said there would be some sleet and snow mixed in.
Icy patches are also something to be wary of where it's coldest, making for "difficult, slippery conditions", warned meteorologist Alex Burkill.
Where to expect snow
Snow is most likely in northern and eastern parts of Scotland, and the eastern side of England, he said, with more on Wednesday and Thursday.
While it will be colder than normal for this time of year in the South, snowfall is unlikely.
But stronger winds toward the end of the week will bring significant windchill, making it feel much colder than even the low temperatures would suggest.
Milder conditions should move in by the weekend.
(c) Sky News 2025: UK weather: Snow possible in parts of country today as temperatures plummet
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