Britain faces further delays and cancellations to travel services after its coldest night of the year.
Clear skies overnight saw temperatures plummet below the -12.4C recorded on Saturday night, with -13C recorded in Shropshire.
Yellow weather warnings for snow and ice are in place until 11am on Tuesday, covering large parts of the country, including London and the South East, much of the Midlands, Northern Ireland and Wales, as well as the eastern coast of England and parts of Scotland.
At Heathrow, where dozens of flights were shelved on Monday, 16 departures are listed as cancelled for Tuesday with the airport advising passengers to check the status of their flight before travelling to the airport.
Cancellations are also reported at Birmingham, Manchester and Edinburgh airports.
Airlines had previously said the re-positioning of aircraft and crews from previous days was adding to the problems.
National Rail is not reporting any major disruption to train journeys owing to the weather - but added services running to and from London Waterloo could be disrupted until 10am following a line-side fire on Monday.
Dozens of schools in the South West, West Midlands and Wales will keep their gates closed for a second day following the bitterly cold conditions.
The country will also wake up to freezing fog patches with rain and hill snow expected later in the day.
Additional reporting by agencies
