People in North London, Cambridge and parts of Surrey and Kent may even see a scattering of snowflakes on Saturday evening, weather charts predict
SCOTS celebrating Halloween could see temperatures dramatically fall, bringing up to four inches of snow over the weekend.
In some higher northern spots the mercury could tumble down to a bitter -5C, forecasters warn.
Cold Arctic air is set to sweep across the UK, bringing a much more wintry feel and heralding the start of the chillier season.
Snowfall is expected to come with this plume of freezing air.
And although mainly restricted to mountainous areas like the Highlands, some southern parts of England could also see some flurries.
North London, Cambridge and parts of Surrey and Kent may see a 0.5cm scattering of snowflakes on Saturday evening, weather charts predict.
The Welsh mountains and Snowdonia are likely to have heavier snowfall on the higher ground, and temperatures close to freezing.
The Highlands and the far north of the country could see up to 4cms of snow, according to Ventusy with some forecasters predicting even more snow to fall over the weekend.
Brian Glaze, director and forecaster for the Weather Outlook, told The Sun Online: "The cold conditions are expected to push southwards on Friday and in the north showers could begin turning to snow. By Saturday all of the UK is likely to be under a cold northerly air stream.
"Showers are expected with most of them in coastal districts and the north, where they could increasingly turn to snow.
"Over high ground in the north settling snow is possible and the Scottish mountains could see accumulations of 5cm to 10cm.
"The northerly air stream is looking quite unstable and it leads to the possibility of embedded disturbances in it bringing more organised bands of showers southwards.
"If that happens, it's not out of the question that in heavier bursts rain could turn to snow even in the southern half of the UK, especially over high ground.
"It would be very unusual to see snow so early in the season in the southern half of the UK, but October 28th 2008 brought a covering of snow even to central London, so it is not completely out of the question.
"Ironically this weekend marks the 10th anniversary of that event and computer models are predicting similar weather patterns.
"By Sunday high pressure may be pushing in from the west and that could lead to a widespread frost. Temperatures in much of the UK could fall below freezing point and in the Scottish Glens values could dip below -5C (23F).
"Cold weather probably continues early next week but there is a risk of it turning wet."
After a chilly start to the week temperatures are set to tumble further with snow arriving by Friday, with some falling as far south as the Welsh mountains, the Met Office confirmed.
Following balmy autumn temperatures reaching 21C last weekend, a rare weather set up will see snow showers in Scotland and northern England, with gale-force winds also set to lash some regions.
The Met Office predicts strong gusts will continue in the north today as sunshine appears again for southern and eastern areas.
The wind should die down through Wednesday and Thursday, but from Friday temperatures will fall and the country will feel distinctly wintry.
Heavy blustery showers will set in from Saturday, with snow likely to fall over northern hills.
As we move into November the Met Office predicts the weather will be "changeable", with more frost and "staying on the cold side".
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