Several weather warnings have been issued for freezing fog, which can cause air pollution and make driving conditions difficult as a cold snap.
The Met Office said the haze would be so thick that visibility could be reduced to 50 meters in parts of England.
A yellow weather warning is in place for between midnight and 11am on Sunday, with thick fog expected to see from Yorkshire to East Anglia.
A “moderate” air pollution warning has also been issued for London by Mayor Sadiq Khan, where hazy conditions are causing poor dispersion of vehicle emissions.
He added: “On Sunday, along with extremely cold temperatures, we are also expecting moderate to high levels of air pollution.
“We all need to be careful in the next few days.
“I am urging Londoners to walk, cycle or take public transport, avoid unnecessary car journeys, prevent engine idling and not burn wood or garden waste, all of which contribute to high levels of pollution Huh.
“This is especially important for protecting people who are more sensitive to high pollution.”
But Met Office meteorologist Craig Snell said the worst of the cold spell was over, with temperatures expected to rise across Britain next week.
Mr Snell said: “Looking at the severe front, next week, it’s looking pretty benign.
“We’re starting to see the risk of fog subside and temperatures are generally around where they should be.
“We’ll probably lose some really hard frosts. In terms of snow and ice, it certainly looks like we’re past the worst.”
“We generally have to keep an eye on the risk of fog this winter, although the main threats from it are starting to subside.”
Nighttime temperatures across the country are still forecast to be sub-zero during the weekend, and will climb to highs of around 5C in the southeast and 10C in the north.
Mr Snell explained that temperatures would be lower in the south – which is often warmer than other areas of the country – due to a change in wind direction to the north west.
The change will lead to an arctic blast that has swept across the UK over the past five days giving way to warm air from the Atlantic, but will take longer to reach southern regions.
Several sporting events were canceled and travel canceled on Saturday due to the severe cold.
The Sky Bet Championship match between Blackpool and Huddersfield was postponed due to a frozen pitch and a race meeting at Haydock was canceled due to an icy track.
CalMac Ferries, which operates services from mainland Scotland to the islands off its west coast, also canceled sailings due to the weather.
National Rail said there was disruption to trains due to a single point failure between Wessex and three bridges in Brighton, Hove and Sussex, but did not specify whether this was caused by snow.
It comes after temperatures fell to minus 10 degrees Celsius amid icy and snowy conditions in parts of the UK this week.
Drumnadrochit, near Inverness in the Highlands, recorded minus 10.4C in the early hours of Thursday, making it the coldest temperature ever recorded for the year.
(tagsto be translated) Met Office