Tuesday night was the coldest night of the year so far, the Met Office has said.
Temperatures at Kinbrace in the Highlands dropped to this year’s record low of minus 15.2C overnight – and snow is on the way for much of the UK through the rest of the week.
Night-time sub-zero climes are predicted in all four UK nations until at least Friday.
Following a “very chilly” start to Wednesday, the Met Office has issued several yellow weather warnings for snow and ice which may lead to injuries from slips and falls and cause travel disruption.
Flights from several airports have been hit by delays, including at Bristol Airport which has temporarily closed for “snow clearing operations” until the next update at 11am.
At least 27 flights due to depart from the airport on Wednesday morning have been affected, while several arrivals have been diverted to Birmingham.
A spokesperson said “additional staff are on site to assist with the adverse weather response” and passengers have been advised to check with their airline prior to arriving at the airport.
Gatwick Airport said some passengers experienced “minor delays” on Wednesday morning but “the airport is open and flights are operating”.
The warnings for Wednesday cover northern and eastern Scotland until 10am, and Northern Ireland and southern England until 9am.
Forecasters have said in most places the snowfall will continue until Friday, with a yellow warning for snow covering all of the UK north of Birmingham spanning from 3am on Thursday until 6pm on Friday.
A yellow warning for snow and ice also covers London and the south from midnight on Wednesday until 9am on Thursday.