The last day of the UK's cold snap will bring freezing rain, treacherous ice and 80mph winds, according to the Met Office.
Roads and paths could quickly become dangerous and impassable in northern Britain as the temperature plummets to between -5C and -8C overnight, forecasters warned.
Strong winds will also lash western Scotland and Northern Ireland, potentially generating large waves and causing disruption to travel.
However, milder air from the west is expected to push away the recent bitterly cold air from the east by Monday, when temperatures could rise as high as 13C.
The return to average weather conditions – including spells of rain and wind – due to last for the rest of the month although the east and southeast is likely to be dryer and more settled than the west and northwest.
Met Office forecaster Luke Miall said Sunday will not be "particularly pleasant".
He said: "It's going to be a bitterly cold day. Certainly where you've got freezing rain and ice, combined with those strong winds."
The weather will be "quite wet and windy" for most of the week, he added. "We will be hovering between 7C to 12C, I suspect, through Tuesday, Wednesday Thursday.
"Most of the snow will start melting early in the week, with the exception being Scotland because they have had so much of it."
A yellow weather warning for ice is in place for most of Scotland, northern England and the Midlands until 9pm on Sunday, and a warning for wind for coastal areas in western Scotland and Northern Ireland's east coast will be in place between 4am and midnight on Sunday.
Public Health England (PHE) has extended its cold weather alert through the weekend and has urged people to check on vulnerable relatives and neighbours.
Dr Owen Landeg, group leader for extreme events and health protection at PHE, said: “Cold weather can have a serious impact on health, particularly for older people and those with heart and lung problems, as it increases the risks of heart attacks, strokes and chest infections.”
This week's cold snap saw the lowest UK temperature since 1995 at Braemar in Aberdeenshire on Wednesday night, with -25C.
A record low temperature for February was also recorded in England and Wales when temperatures in Ravensworth, North Yorkshire, dropped to -15.3C overnight on Thursday.
The chill froze Trafalgar Square's fountains and parts of the River Thames in London, and turned the Kinder Downfall in Derbyshire's High Peak area into a 95ft climbing wall of ice.
On Saturday afternoon the Metropolitan Police’s marine unit tweeted footage of its boat cracking the ice on the Regent’s Canal in London, adding: “We’re on thin ice today! Our patrols are more like a polar expedition.”
Additional reporting by Press Association
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