Londoners have been warned of possible travel disruption throughout Sunday as a “freezing fog” hits large parts of England.
Mayor of London Sadiq Khan also issued a “moderate” air pollution alert as still, foggy conditions make it harder to dissipate toxic fumes.
The Met Office’s yellow weather warning between 2am on Sunday and 11am on Monday affects a large part of England, including much of the south and west of the capital.
Forecasters predict lows of -3C for London on Sunday alongside the fog, but the cold temperatures are set to warm up throughout next week.
Met Office meteorologist Craig Snell said: “Next week, looking at the severe front, it’s looking pretty benign.
“We’re starting to lose the risk of fog and temperatures are generally around where they should be.
“We’ll probably lose the really hard frosts. In terms of ice and snow, it certainly looks like we’re over the worst.
“We’ve got to keep an eye on risk of fog generally this cold spell, although the main hazards from it look like they are beginning to diminish."
Mr Snell explained the temperatures would be lower in the South - which is often warmer than other areas of the country - because of a change in wind direction in the North West.
The change will see an Arctic blast that swept across the UK over the past five days giving way to warmer air from the Atlantic, but will take longer to reach southern areas.
The Mayor of London, Sadiq Khan, said: “On Sunday, alongside the extreme cold temperatures we’ve been experiencing, we are also expecting moderate to high levels of air pollution.
“We all need to be careful over the next few days. I’m urging Londoners to look after each other by choosing to walk, cycle or take public transport, avoiding unnecessary car journeys, stopping engine idling and not burning wood or garden waste, all of which contributes to high levels of pollution.
“This is particularly important in order to protect those who are more vulnerable to high pollution.”
The warnings came after several sports fixtures were called off on Saturday amid freezing conditions, while some train services experienced disruption.
The Sky Bet Championship match between Blackpool and Huddersfield was postponed due to a frozen pitch.
National Rail said there was disruption to trains between Three Bridges in Wessex and and Brighton, Hove and Sussex due to a points failure but did not specify whether this was caused by ice.
It comes after temperatures plunged below minus 10C in parts of the UK this week amid snow and icy conditions.
Drumnadrochit near Inverness in the Highlands hit minus 10.4C in the early hours of Thursday, making it the coldest recorded temperature of the year so far.