Large parts of Scotland, northern England and Ireland are being warned to brace themselves for snow and ice, with weather warnings issued as temperatures plummet.
The United Kingdom and Ireland are copping a blast of cold air from northern Scandinavia, resulting in a cold snap for many in the north.
Daytime temperatures are expected to drop to cold, single-digit figures this week.
There is more bad news for those missing the summer warmth as frigid temperatures will likely continue into next week.
There are two yellow weather warnings in place for the United Kingdom, one for snow and ice until 11am on Wednesday for parts of northern and eastern Scotland, north-east England and Yorkshire, and a second set until 11am on Thursday for eastern Scotland and north-east England down to North Yorkshire.
People living in those areas are advised to expect showers throughout Wednesday morning that will likely see ice form on untreated surfaces, which may make some roads and pathways hazardous and slippery.
Snow is also expected, especially for people in places away from windward coasts, with the Met Office predicting up to three centimetres of snow will fall.
The Met Eireann has issued a yellow fog warning for large parts of the Republic of Ireland and the Met has also issued a yellow warning for Northern Ireland until 10am with people urged to be wary of icy conditions.
In Scotland, the Met warns that people may see up to five centimetres of snowfall in higher parts of the northeastern parts of the nation.
Some roads and rail services are likely to be impacted, with Britons warned to prepare for longer or delayed journey times on roadways, railways, and public transport.
Those unable to stay home as conditions turn icy and slippery are encouraged to plan their journeys using the relevant traffic websites for Scotland, England, Wales, and Northern Ireland.
The UK Health Security Agency (UKHSA) has issued warnings of its own, with yellow and amber cold-health alerts for northern regions of England until December 5.
Met Office deputy chief meteorologist David Oliver warned of an uncertain weather period on Thursday and Friday for the southern half of England and Wales.
“The weather models are highlighting several possible solutions from very wet to mainly dry, with a mainly dry picture the most probable outcome at present,” he said.
“However, some models include the prospect of an area of low pressure developing and moving in from the south or south-west.
“If this solution proves to be correct, we could see an area of warmer and moisture-laden air ‘bumping’ into the cold air further north. Along the boundary of the two air masses lies a zone across southern and central Britain where snowfall could develop fairly widely.”
He added: “Snow in any affected area is unlikely to be anything more than transient and short-lived, but it could lead to small totals and some disruption over a few hours before melting.”
Snow is not expected to linger as ground temperatures usually remain relatively high at this time of year compared to late winter after the ground loses more of its warmth.