Drivers and other travellers are facing difficult journeys as Icy Conditions Persist across much of the UK.
Hundreds of schools are remaining closed for a second day.
A low of -13C (9F) was recorded on Monday night in Shawbury, Shropshire - the coldest night of the year so far.
The Met Office's warning covers Wales, parts of Scotland and much of England - including the Midlands, Yorkshire and Humber, London, the South East, East, South West, the North East and North West.
BBC News.