Snowfall and icy conditions are expected to cause widespread travel disruption on Friday morning after temperatures plummeted as low as minus 15.4C (4.3F) overnight.
A pivoting system of wintry weather means much of southern England and Wales will wake up to more of the white stuff after the coldest night in the UK since 2012.
An amber snow warning has been issued for an area west of London including parts of Oxfordshire, Hampshire and Buckinghamshire, with stranded vehicles and power cuts “likely”, and a “good chance” some rural communities could be cut off.
The alert comes after as much as 14cm of snow wreaked havoc in the south-west on Thursday.
Efforts to rescue motorists stranded on snowbound roads in Devon and Cornwall continued through the night, while hundreds of people were forced to find shelter where they could.
Meanwhile, persistent snow began to spread across the south east late on Thursday and flurries were seen all the way into central London.
The Met Office has also has two yellow weather warnings of snow and ice in force until Friday afternoon covering southern England and Wales, as well as the eastern edge of the UK from Shetland to The Wash.
Police forces across the country are warning motorists to consider if their journeys are necessary before heading out on Friday and be “extremely careful” if have to travel by road.
On the rail network Southeastern and Transport for Wales have altered their services on Friday as a result of the adverse conditions.
The South Western Railway was planning to run a normal timetable, but warned some early services may need to be cancelled as routes are cleared.
Meanwhile Southern, Thameslink, Great Northern and Gatwick Express were expected to run normally, although all passengers were urged to check before they travel in case the conditions impact services.
Transport for London also advised passengers to check their service status before setting off.
Airports were also hit by the freezing weather, with Bristol Airport suspending flights until 8am while the runway was cleared.
Snow was also seen falling at Heathrow on Friday, where British Airways altered a number of short-haul flights on Thursday, and passengers using the hub were being told to stay in contact with their airlines before travelling.
Gatwick Airport also saw flurries, although the airport was advising passengers it was planning on operating as normal on Friday.
Met Office meteorologist Emma Smith said: “There is still sleet and snow across southern counties, the band is currently sitting across the south-west and Wales and across to East Anglia and London.
“It’s kind of pivoting in place and it’s not really moving very far. What will be happening to it is it will get patchier as it goes on, but it could cause some disruption to rush hour.
“Temperatures are widely below freezing so there’s icy stretches so people will have to take care going into work.”
By lunchtime temperatures in the South East are expected to nudge towards 4C, meaning the sleet and snow should turn to rain.
However the rest of the country, with the exception of southern Scotland and Northern Ireland, is expected to see wintry showers persist into Friday evening.
“Into the afternoon those showers will go into the Pennines and the Peak District as well,” Ms Smith said.
The Met Office said a low of minus minus 15.4C (4.3F) was recorded just before midnight at Braemar in the Scottish Highlands.
Had it fallen more than 0.2C (0.4F) lower it would have surpassed the low of minus 15.6C (3.92F) set in 2012.
More than 100 people sought shelter at the Jamaica Inn on Bodmin Moor after scores of vehicles were stranded the A30.
Some students at Callywith College around 10 miles away were forced to stay the night after buses were unable to leave.
Across Devonshire 34 schools have said they will be closed or partially closed on Friday and 35 schools across Cornwall have also said they will not be opening, according to the two county councils.