Snow and ice weather warnings are in place for much of England and Scotland after widespread recent snowfall.
The Met Office has issued yellow weather warnings across England and Scotland for Saturday and warned of possible travel disruption.
Parts of England and Scotland could see as much as 5-10cm of snow in higher areas, the weather service said.
It comes as hundreds of schools remain closed after heavy snow hit the north of England on Thursday.
A snow warning is in place for south-east England, including London, the east of England and the East Midlands. The Met Office said East Anglia and parts of Kent and Sussex are most at risk of snow.
Some 1-3 cm of snow may fall fairly widely over these areas, with 5-10 cm possible in places, mostly over parts of East Anglia and any higher ground.
A snow and ice warning is in place for most of Scotland, north-west and north-east England, Yorkshire and Humber, the East Midlands and parts of the West Midlands.
Snow is likely to fall to low levels over east Scotland and northern England.
The Met Office said 1-3 cm is possible at low levels in these areas but is more likely at higher elevations, where 5-10 cm of snow is possible above 200m - and even 20cm at the highest places.
Fog is also forecast for parts of the Midlands and the North, along with mist around Glasgow which may pose hazards for motorists.
The coronavirus vaccine rollout has been affected by the weather.
Over-80s who were due to receive their jab at Newcastle's Centre for Life were told they could re-book rather than risk making a trip in the icy conditions.
Newcastle Hospitals tweeted: "There's enough vaccine for everyone, so don't worry about making a trip to Newcastle."
And Leeds University has delayed the opening of its asymptomatic Covid-19 test centre.
Heavy snowfall has already caused travel disruption across sections of northern England and Scotland.
Temperatures were as low as -6C on Friday morning in parts of Yorkshire and Cumbria, with yellow warnings set to last through most of Friday.
There was a loss of gas supply to approximately 700 homes in the Hebden Bridge area after water got into the local gas network and froze.
The Met Office has published advice from the Department for Transport advising people to clear snow and ice from footpaths outside their homes, preferably in the morning.
"You can then cover the path with salt before nightfall to stop it refreezing overnight," the advice says.
Temperatures in the Greater London area are expected to drop to 1C on Friday and parts of the South East could fall to -2C.
Mark Millins, of Yorkshire Ambulance Service NHS Trust, said the bad weather was having a "severe impact" on its operations and urged people to "take extra care" when out walking or driving.
In Scotland, heavy snow in some areas resulted in road closures.
The deepest snow on Thursday was in Bingley, West Yorkshire, and Strathallan in Perth, Scotland, both of which recorded 11cm.