A five-day cold weather alert has been issued for much of England with a -11C Arctic freeze on its way from Norway.
The Met Office issued a Level 3 amber cold weather warning for most of the country and is urging Brits to take care in the freezing conditions.
It will remain in place from 6pm on Wednesday until 9am on Monday, with overnight temperatures plummeting to -6C in some parts of Britain.
While daytime temperatures will still be at freezing point for some regions, with the mercury struggling to climb above a bitter 0C.
People are being urged to use their heating despite rising energy prices, and to look out for people who are especially vulnerable.
The cold snap can have a serious impact on the health of older and more vulnerable people, the alert warns.
Met forecaster Oli Claydon said: “Day to day we are in cold conditions already with that north-easterly flow.
"But conditions are set to get colder through the week, with the worst showers across northern Scotland but also bringing much colder conditions across all the UK.
“Overnight lows of -10C to -11C in areas where we do get snow in those rural parts of Scotland, with temperatures down to -6C in rural England."
The level 3 weather and health warning is agreed by the UK Health Security Agency (UKHSA) and alerts social and healthcare services to take action to protect high-risk groups.
Frost is also expected along with a 90 per cent chance of severe cold weather and icy conditions.
The Met Office also issued a yellow warning for ice for Wednesday and Thursday, which will be in force in parts of Wales, Northern Ireland and England’s east coast.
This applies from 6pm on Wednesday until 6pm Thursday, or midday in the east, with Brits warned to look out for icy patches on untreated roads, pavements and cycle paths.
Snow is likely in northern Scotland, although temperatures will be low enough to make it a possibility anywhere in the country.
The big freeze may come as a shock to Brits after a mild autumn for much of the nation.
A yellow weather warning for snow is also in place for northern Scotland from midnight on Wednesday until Thursday at midday.
Cold conditions are expected to turn even colder across much of the UK later on Wednesday and through to Thursday as air from the Arctic spreads south across the country.
Frosty nights are expected, with subzero temperatures and widespread frosts which could be severe in some areas.
Daytime temperatures are expected to linger near or just above freezing, with overnight temperatures continuing to drop further.
Some coastal areas are likely to be lashed with wintry showers which could push inland with a risk of icy patches.
A Met Office spokesperson said: "Look out for friends and family who may be vulnerable to the cold, and ensure they have access to warm food and drinks and are managing to heat their homes adequately."
"Try to maintain indoor temperatures to at least 18°C, particularly if you are not mobile, have a long-term illness or are 65 or over.
"Avoid exposing yourself to cold or icy outdoor conditions if you are at a higher risk of cold-related illness or falls and stay up to date with the latest weather forecasts on the Met Office website."
