Temperatures are expected to plunge to as low as -7C next week after a mild weekend.
Sunday could see highs of 16C, although some of the UK will be hit by wet and windy weather, according to the Met Office.
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A temperature drop into the start of next week will bring sub-zero conditions and extensive frost overnight on Monday, said Sky News weather producer Chris England.
He said the return of wintry conditions would bring "a risk of icy stretches and some dense freezing fog".
"Rain spreading from the west on Tuesday will turn to snow on northern hills as it moves into the cold air," he said.
"There's the potential for some disruption on the higher routes.
"The cold weather will linger in the north into Wednesday, but it'll be turning milder in the south," he added.
The highest temperatures will be in south-west England on Sunday.
The colder weather will start on Monday, with temperatures expected to be slightly below average, and showery outbreaks of rain and northerly wind.
Tuesday is predicted to see a band of rain gradually moving in from the west.
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"Temperatures on Monday could fall as low as about -7C in parts of rural Scotland overnight. That is likely to be the coldest night of the week," Met Office spokeswoman Becky Mitchell said.
Ms Mitchell said mild weather this weekend would bring highs of around 15C in southeast England, with top temperatures of up to 16C in the southwest on Sunday.
"It will be quite wet and windy though, we will have various bands of rain coming in from the west, which could be heavy at times, and also very breezy across the whole country," she said.
"The rain will be heavy in places, but we're not expecting any large amounts to cause any significant issues."
"The temperatures this whole time will be around mid-single figures, so feeling pretty chilly. We will have some overnight frost as well, particularly on Monday night," said Ms Mitchell.
"Thereafter temperatures are probably turning average from midweek, with rain at times and some dry interludes too."
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