A MET Office map has revealed where temperatures will plunge across the country tonight with 80 areas put on alert for flooding.
Brits are braced for more wintry weather after heavy rain and strong winds earlier this month.
The Environment Agency still has 18 flood warnings in place across England, mostly for the River Severn and River Derwent.
There are also 62 flood alerts, coloured in amber, active.
The overnight UK minimum was -11C at Tyndrum in Stirling, while -5C was recorded in Scottish cities including Edinburgh, Aberdeen and Dundee.
Further south, England’s lowest temperature this morning was -2.9C in Keswick, Cumbria.
It comes after Storm Darragh wreaked havoc and claimed lives across the country.
The final homes without power are set to be reconnected today as deluged residents clean up following the deadly 92mph storm.
Tonight, temperatures are expected to fall to -4C in Scottish towns and cities, while Wales will drop to 1C and South East England will fall to 4C.
Met Office meteorologist Alex Deakin said: “The weather today is pretty similar to yesterday’s weather – starting very cold and frosty across Scotland and Northern Ireland and some dense patches of fog here, which are going to linger all day.”
Tonight will be mostly cloudy across England and Wales with some light drizzle in the East, while clear spells and a frost will develop in some areas.
Mr Deakin said: “For the vast majority it’s a dry night, but through the early hours thickening cloud over eastern parts is likely to bring some rain and drizzle back in here.
“Temperatures again, with the cloud, holding up above freezing. Where it’s clear, well below freezing across Scotland, -3C (27F) to -4C (25F). That’s towns and cities – some sheltered glens much, much lower than that.
“So again, a fairly hard frost and again some fog around which will again in parts of South West Scotland last for most of the day.”
Conditions will remain cloudy tomorrow with patchy drizzle, mostly in the East – while low cloud will lead to hill fog in places. Brighter skies will be seen in the West and across much of Scotland.
Mr Deakin said of tomorrow: “Much of Scotland away from the fog will be dry and sunny. Perhaps a bit cloudier for Northern Ireland, thicker cloud for England and Wales.
“That cloud is going to be at times producing rain and drizzle – so a dank, dreary, pretty dismal kind of day for a quite a good chunk of England.
“Some of that rain and drizzle into parts of Wales at times too. Much of the South I suspect will be dry but still gloomy and still cold.”
Temperatures tomorrow are expected to get up to 8C in England, 6C in Wales, 5C in Northern Ireland, 1C in the Highlands and 4C in the rest of Scotland.
The Met Office expects high pressure to continue to dominate from Friday, bringing some sunshine and overnight frost and fog.
However, patchy rain will start to arrive across the North during the weekend as temperatures begin to climb again.