Temperatures in northern parts of the UK could fall as low as minus 20C on Friday night as wintry weather continues, the Met Office has said.
There are yellow warnings for ice on Friday morning covering the eastern coast of England and Scotland, the South West, Wales and Northern Ireland.
There is also a yellow warning for snow and ice for northern Scotland. All the warnings expire before midday.
In addition, freezing fog is predicted across central and southeast England, and in parts of Wales, which may be "quite stubborn to clear" on Friday morning, said Met Office meteorologist Liam Eslick.
"It's going to be another cold couple of days," he added, and all areas of the UK are likely to experience sub-zero temperatures.
The Met Office confirmed that Thursday into Friday was the coldest night of winter so far in the UK, with the temperatures falling to minus 14.5C in Altnaharra, in the Scottish Highlands.
It was the coldest January overnight temperature since 2010 - which was a month that saw temperatures drop below minus 15C several times at locations across the UK, including minus 22.3C on January 8 in Altnaharra.
Temperatures could plummet as low as minus 15C or even minus 20C on Friday night.
"That's probably the lowest limits we're expecting," Mr Eslick said.
"We probably don't really expect many places to get close to minus 20C, but we could see one or two places that could just touch that mark overnight Friday into Saturday."
That is because of still conditions, high pressure, "not a lot of wind and clear skies".
In addition, snow on the ground helps to create "sort of a perfect scenario to see those temperatures just plummet", Mr Eslick added.
Saturday is also likely to be bitterly cold, while Sunday is forecast to be a little warmer.
On Monday, temperatures are expected to be more in line with the seasonal norm, at about 7-8C.
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The freezing conditions have led to travel disruption, with Manchester Airport closing both its runways on Thursday morning because of "significant levels of snow". They were later reopened.
Transport for Wales closed some railway lines because of damage to tracks.
Hundreds of schools in Scotland and about 90 in Wales were shut on Thursday.
Meanwhile, staff and customers at a pub thought to be Britain's highest were finally able to leave on Thursday after being snowed in.
The Tan Hill Inn in Richmond, North Yorkshire, is 1,732 feet (528m) above sea level.
Six staff and 23 visitors were stuck, the pub said on Facebook.
(c) Sky News 2025: UK weather: Temperatures could fall as low as -20C after UK records coldest night in 15 years