Swathes of the country are braced for brutal -14C (6.8F) Polar gales, heavy rain, sleet and snow as the fury of the Arctic is unleashed across the nation.
Britons are warned to wrap up through the weekend with thermometers unlikely to rise above single figures anywhere on Saturday.
The mercury will plunge lower than Russia, Greenland and Iceland will freezing winds making it feel colder than parts of the Arctic.
Bitter cold will hold out into the start of next week before a horror storm tears into the UK from the Mediterranean.
Parts of south-east England are on alert for torrential downpours and powerful gales on Tuesday as autumn cranks up the weather misery.
Freezing Polar air started to edge into Britain today as forecasters warned a nationwide Polar plunge will hit tonight.
The Met Office has issued a severe weather warning for snow and ice across Scotland until just before lunchtime tomorrow.
Meteorologist Matthew Box said: “Northerly winds will bring a full Arctic blast across the country overnight after a pretty chilly day on Friday.
“Temperatures will drop widely into low single figures and it is going to be windy in parts, there is a risk of gale-force gusts in coastal regions and this will make it feel especially raw.
“Wintry showers will be more widespread on Saturday and there will be a band of heavier showers pushing down the east coast of Great Britain although snow will largely be confined to high ground.
“Saturday will be even colder than Friday and during the day temperatures are going to struggle to get out of single figures with lows in minus figures overnight, we could see -6C (21.2F) in some spots.”
Temperatures will hit a maximum of around 8C (46.4F) during Saturday before creeping back into low double figures on Sunday.
A bitter cold airmass from the North Pole will wedge over Britain into next week before the weather starts to turn milder but more unsettled, Mr Box added.
He said: “Sunday will be widely very cold although winds will be lighter across much of the country apart from in southern regions where they could be stronger.
“Monday will be another relatively cold day with temperatures below average for the time of year.
“There is quite a bit of uncertainty after that but Tuesday is looking more unsettled in the southeast with some persistent rain and strong winds.
“This is due to a low-pressure system over Iberia which we expect to move into the UK affecting our weather.”
UK weather charts show temperatures plummeting to -4C (24.8F) in Scotland and northern England tonight with parts of Wales dipping below freezing.
Saturday night will be even colder with lows of -6C (21.2F) in northern Britain and freezing or just above elsewhere.
Temperatures in Britain are about to drop lower than Moscow, Russia, Reykjavik, Iceland and Greenland’s capital Nuuk.
Numbing Arctic gales over the next 48 hours will make it feel even colder than the Arctic Svalbard Islands off the north coast of Norway where temperatures are expected to remain around -9C (15.8F).
Weather charts show freezing winds sweeping the UK will bring ‘feel-like’ temperatures of -14C (6.8F) across Scotland and northern England and between -4C (24.8F) and -7C (19.4F) further south.
It is likely to be the coldest October weekend since 1993 when the mercury dropped to -9.2C (15.44F) on Saturday the 16th in Shap, Cumbria, and -9.9C (14.18F) in Carnwath, Lanarkshire, in Scotland, the next day.
Snowfall is most likely across the hills and mountains of Scotland and the north over the next few days although there could be flurries down the east coast.
Some forecasters warn sleet or snow could reach as far south as London with violent thundery eruptions triggering outbreaks of thundersnow.
Exacta Weather forecaster’s James Madden said: “The risk of wintry showers will be greatest from early Saturday with showers most likely across northern regions but possible further south and across parts of Wales.
“There is a small chance of some wintry precipitation as far south as the Capital although this is not likely to be significant.
“Where there is snowfall, a contrast between cold and warm air could lead to unstable atmospheric conditions triggering thundery outbreaks and a risk of thundersnow.
“This weekend will see the first cold snap of the season really take hold.”
Government weather warnings for snow and ice are in place across Scotland tonight and tomorrow morning with a separate ice alert covering Northern Ireland.
Met Office chief forecaster Frank Saunders said: “A mix of rain, hail, sleet and upland snow showers, some heavy, will leave many roads wet tonight and into Saturday morning allowing patchy ice to form.
“Over upland routes above around 200 to 300 metres some slushy snow deposits could occur, more notably on hill routes above 400 metres.
“Travel conditions could become difficult and hazardous, especially on untreated surfaces, or where showers wash away grit or salt.”