BRITAIN will be blasted by up to 4in of snow as the big freeze tightens its grip.
The South will be hardest hit over the next 48 hours.
The Met Office issued alerts for London and the South East yesterday after temperatures fell to -9C.
Britain was hit with its coldest night of the year-so-far as a bitter -9.2C was recorded in Eskdalemuir in Scotland on Friday night.
And the weather service warned of a possible -15C on coming nights, with daytimes barely above freezing.
The North and South Downs are likely to get most snow.
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The UK Health Security Agency issued a rare level three alert, warning the vulnerable to heat homes to 18C.
It comes as arctic conditions continued to freeze the nation today as temperatures plummeted, with numerous yellow weather warnings for snow and ice issued by the Met Office.
Councils have stockpiled 1.4million tons of salt but 63 per cent are struggling to find HGV drivers to grit roads.
The Met Office has warned of freezing weather over the weekend, as well as wintry showers.
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And the weather service issued a yellow snow and ice warning for London and the South East from 9am on Sunday to 9am on Monday.
The UK forecaster said: "Snow may push in across parts of east and south-east England, leading to a risk of travel disruption especially on Monday morning."
The weather service have also issued a Level 3- Cold Weather Action alert, extending the existing alert all the way to next Friday December 16.
Cold weather is now established across the country with "very cold nights" expected over the weekend into the early part of next week.
Temperatures nearly hit -10C last night in what was the lowest recorded in England for December in almost a decade.
While the 'Troll of Trondheim' caused disruption by forcing many schools in Scotland to close or delay their opening times yesterday.
A Met Office forecast for today said it would be a "frosty start" with "very cold" temperatures particularly in rural areas.
Most parts of the country will see highs barely above freezing over the course of the day.
The Met Office said: “Despite some sunshine, temperatures will barely climb above freezing in some areas.”
And forecasters have warned drivers that wintry showers will create further hazardous, icy patches on some roads this weekend.
The weather service also urged pedestrians to be careful because of icy surfaces or risk injury.
Four people have already been killed across the UK in road traffic collisions as motorists tackled dangerous icy roads.
A number of schools in Scotland were forced to shut on Thursday because of the severe cold weather with 5cm of snow falling in Aboyne, Aberdeenshire, and at Althnaharra in the Highlands.
Met Office chief meteorologist Steve Willington warned there is an “increasing risk of snow as the week progresses”.
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It comes after 2,000 homes in Sheffield were left without heating for five days, with a major incident declared.
London Mayor Sadiq Khan has also agreed emergency planning, which includes sheltering homeless people from the severe weather.