Motorists in the UK have been warned of dangerous conditions on the roads and air travellers of potential disruption as snow and ice hit large swathes of the country.
Thousands were left without power as wintry weather swept in overnight, with Western Power Networks saying more than 14,000 properties had been cut off.
The southbound carriageway of the M1 was closed near Lutterworth in Leicestershire after an accident involving a lorry, while another HGV jack-knifed in heavy snow on the M5 in Gloucestershire.
Meanwhile, passengers at Birmingham Airport were warned that snow could impact flights.
The British Met Office has issued a yellow warning of rain and snow for the Midlands, London and the South East, the North West, South West and Yorkshire and the Humber that will remain in place until 11am.
A separate warning for ice has been issued for Northern Ireland, Yorkshire and the Humber and the North East in England and the Highlands, Grampian, Lothian Borders, Strathclyde and Orkney and Shetland in Scotland.
The Flood Information Service has also issued 14 warnings, where flooding is expected and immediate action is required, and 96 alerts where flooding is possible and people should be prepared.
British Met Office meteorologist Simon Partridge said: "We have had some quickly changing weather overnight with a band of heavy rain and hill snow that started in the south west and is gradually moving north and eastwards.
"That's crossed Wales and is just lying over central southern England and it has brought some snow with it."
Up to 7cm of snow was recorded to have fallen over Exmoor, South Wales and the Cotswolds overnight, while other areas also saw flurries.
"We have had a number of reports of areas affected; it shut part of the M5 just south of Bristol because lorries could not get uphill," Mr Partridge said.
Heavy snow has started.. The M1 has quickly become treacherous ..— Northants Police ARV (@NorthantsARV) December 27, 2017
RAPT on scene at a single vehicle RTC..
Drive to the conditions, not the limit.. pic.twitter.com/MBGbi3uZG0
"There has also been come power cuts reported and road traffic accidents as well, although these have been more to do with surface water."
Strong winds were also recorded in parts of the south west overnight, with gusts of up to 50mph blowing across Cornwall.
The band of rain and snow is not expected to clear the mainland until around 7pm on Wednesday, although showers are expected to become lighter and patchy as the day progresses.
Dry, bright and breezy conditions will follow, with some wintry showers affecting the west and north of Wales and Northern Ireland.
Temperatures are expected to peak around 6C (43F) in the South West, although many places will only reach 3C (37F) or 4C (39F).
Places where snow has accumulated overnight will struggle to tip over 0C (32F), while those areas could see temperatures dip back down to minus 6C (21F) overnight on Wednesday.
Thursday will generally be drier and day with slightly less wind, although it will remain cold.
Wet and windy weather is expected to return for the weekend, raising the risk of some flooding, Mr Partridge said.