The first day back at work following the new year festivities is set to be "much colder" than recent mild conditions, after temperatures plummeted as low as minus 6C overnight, forecasters have said.
Those heading out early in the morning will have to wrap up and consider allowing extra time for cars to de-ice, with a sharp frost expected first thing on Wednesday.
It is unlikely to climb far above freezing throughout the day in many areas and is due to remain in single figures across the country.
Met Office forecaster Emma Smith said: "It's going to be a pretty cold start to the day - temperatures were down to minus six in Scotland and there has been a quite widespread frost.
"It's dry out there so there won't be a problem on the roads - there's not much moisture around so obviously not much ice around.
"There's only been a few patches of mist near the Scottish border, so it's been quite a clear night in the sense there's not any fog.
"So it'll be fine to drive to work, but it will be cold."
A low of minus 6C was recorded by the Met Office at Glasgow and Braemar in the early hours of Wednesday, while lows of minus 4C (25F) were recorded in North Wales and minus 2C (28F) in the North West of England.
Temperatures are expected to peak at around 7C (44F) in London as the day wears on, with highs of 6C (43F) in Manchester, 4C (39F) in Newcastle and 3C (37F) in Edinburgh.
Ms Smith said: "It will be a dry day and, throughout, the best of the sunshine will be in the west, mainly for Scotland, north-west England, Wales and the South West.
"For eastern areas, we're looking at a cloudy day, and Northern Ireland is largely cloudy as well - but a dry day with really light winds.
"It will be a lot colder than we have had recently. Temperatures in the north, for parts of Scotland, are not getting above plus one (34F) today and in northern England - Carlisle is plus two (36F). It's going to be single figures really for much of the country, even in the south.
"London's expected to get up to seven degrees, but quite a lot of places in the south are between five and six degrees for today - much colder than we've seen of late really."
Temperatures are again expected to plummet on Wednesday evening, leading to chilly weather on Thursday and patches of freezing fog. Many areas of the country are expected to see clear, sunny conditions.
Additional reporting by PA
