Commuters face widespread travel disruption after heavy snowfall and ice affected parts of the UK.
The Met Office put in place a yellow warning for ice for much of southern England, the Midlands and eastern Wales from 5pm on Tuesday to 10am on Wednesday.
Several other warnings for snow and ice have been in force across the UK, with the Met Office advising vehicles could be stranded, power cuts may occur and rural areas could be cut off.
The forecaster on Tuesday warned of snow showers developing during the evening and continuing overnight into Wednesday morning. The showers may be heavy at times and accompanied by lightning in some areas.
Some lying snow could reach up to 10cm or more over higher ground and ice is expected to form on untreated surfaces.
Southern Rail said overrunning engineering works at South Croydon will affect early morning trains between East Croydon and Uckfield/East Grinstead.
The Met Office spokesperson Stephen Dixon said: “We’ve had a fairly mild November so far.
“So it’ll feel like that first taste of winter for many with that snow and ice risk layered on top.
“The highest accumulations are likely over the mountains in Scotland, where over higher ground you could see around 20cm of snow through this week accumulating on the ground.
“They are not necessarily the most disruptive snowfalls, but it only takes a couple of centimetres on lower ground to cause some level of travel disruption.”
There was widespread disruption on Tuesday across the UK, with more than 200 school closures reported by the afternoon.
Snowfall was also widely reported, with 12cm of lying snow recorded at Watnall, Nottinghamshire, on Tuesday morning as an Arctic air mass influenced the UK’s weather.
The Met Office said the coldest temperature was recorded at Braemar village in Aberdeenshire, with the mercury falling to -11.2C on Tuesday.
Thousands of train passengers experienced disruption on Tuesday morning and a Stagecoach bus in Aberdeenshire toppled onto its side with a passenger onboard in icy conditions.
The UK Health Security Agency has issued the first amber cold weather health alert of the season, warning conditions could be dangerous for vulnerable people, including elderly people.
The amber warning covers the east and north of England, the Midlands, and Yorkshire and the Humber, with yellow alerts coming into place for the south-east, south-west and London until 6pm on Saturday.
The Met Office’s chief meteorologist, Neil Armstrong, said: “With cold Arctic air firmly in place over the UK, continued winter hazards are likely through much of this week, with further updates to warnings likely in the coming days.”
skip past newsletter promotionafter newsletter promotion
The Met Office has issued a yellow warning for snow and ice along the east coast of Scotland and England from Berwickshire to Suffolk from 6pm on Tuesday to midday on Wednesday.
A yellow warning for snow and ice has also been issued for Northern Ireland from 6pm on Tuesday to 10am on Wednesday, with a separate warning also in place across most of Wales and parts of the West Midlands until 10am on Wednesday.
Police in Northern Ireland urged those on the roads to “drive with extra caution while we experience the freezing temperatures as forecast”.
There are also snow and ice warnings in place covering the north of Scotland until 10am on Wednesday and parts of western Scotland from 7pm on Tuesday to 10am on Wednesday.
The Met Office said cold northerly winds will continue through the week across much of the UK, with further warnings likely.
It added that temperatures were likely to increase from the south-west this weekend, though this will be accompanied by some strong winds and heavy rain.
The Alzheimer’s Society warned that cold weather can be “particularly challenging” for people with dementia.
“Colder temperatures can be difficult for a person with dementia to adjust to, and they may not always be able to communicate that they are cold - or they may not even recognise it themselves,” the charity said.
Another charity, Asthma + Lung UK, urged those with lung conditions to be “extra careful”.
It said cold weather can trigger potentially life-threatening asthma attacks or “flare-ups” for people with other lung conditions.