Parts of the UK have been hit be snow and ice, with warnings from police in some areas to only travel if “absolutely essential”.
Yellow alerts for snow and ice are in place across large areas of all four nations and an amber alert for snow has been issued for northern Scotland.
In Somerset, a double-decker bus with 70 people on board overturned in icy conditions, injuring dozens.
Overnight temperatures dropped as low as -9.8C and some schools have shut.
BBC forecaster Nick Miller said: “Widespread cold has returned to the UK with lows of -7 to -10C across the four home nations last night.”
Northern Scotland, Northern Ireland and parts of north-west England and Wales are likely to see further snow, he said.
Conditions in the Highlands were expected to “deteriorate”, he said, and travel disruption was likely.
“Temperatures across much of the UK will only rise a degree or so above freezing today with another widespread frost tonight”, he added.
An amber alert for snow is in place for parts of north and north-east Scotland until midnight meaning travel disruption is expected and rural communities are likely to become cut off.
A yellow alert for snow and ice across parts of the UK until midday on Wednesday means travel delays are likely and icy conditions which could lead to slips and falls.
At Loch Glascarnoch in the Scottish Highlands, 32cm (12.5in) of snow fell on Tuesday morning, according to the Met Office.
It will remain cold for the rest of the week, but BBC forecasters say it will turn milder by the weekend.
Avon and Somerset Police warned drivers to “only travel if absolutely necessary” after the force said it received more than 100 reports in five hours due to “treacherous conditions”.
The A39 near Cannington is closed after a crash involving a motorcyclist resulted in a bus overturning.
Avon and Somerset Police said conditions were “extremely icy and dangerous” as a result of freezing overnight temperatures and residual water on the road from last week’s wet weather.
Over in the South East, Kent County Council highways manager Toby Howe warned of flooding issues on the roads after an “awful night” of heavy rainfall.
Car overturned in Pendoylan
In Cornwall, more than 80 schools have been shut and some roads are blocked after heavy snow fell in parts of the county.
Devon and Cornwall Police tweeted, urging drivers to “travel with caution as heavy snow showers sweep through the region”.
Schools in Shetland have been closed for a second day and more than 200 have been shut in the Highlands.
The Met Office said a further 10 to 15cm of snow could fall in a short space of time across northern parts of Scotland.
There have been 19 road crashes across Londonderry and Strabane as snow and icy conditions came in overnight in Northern Ireland.
An amber warning for snow in northern Scotland, covering Inverness and Aberdeen, in place from 15:00 until midnight
A yellow alert for snow and ice for parts of north Scotland until 09:00 on Wednesday
A yellow warning for ice and snow across western England, Wales, Northern Ireland and parts of west Scotland until midday on Wednesday
A yellow alert for snow and ice across Cornwall, Devon and southern Wales from 18:00 until midday on Wednesday
A separate yellow warning for ice across southern England from 18:00 until 10:00 on Wednesday
A level three cold alert was issued on Monday by the UK Health Security Agency and is in place until 09:00 on Friday.
The government health agency warned the severe cold weather could cause health risks to vulnerable people and disrupt services.
London’s mayor Sadiq Khan activated the city’s Severe Weather Emergency Protocol (SWEP) on Monday to provide emergency accommodation for rough sleepers as temperatures fell.
The cold spell comes after widespread flooding left parts of the UK submerged over the weekend. More than 82 flood warnings and at least 116 flood alerts are still active across England.
Breakdown service the AA said it has been responding to around 12,500 incidents on the roads a day this week due the colder conditions damaging road surfaces and creating potholes.
It added this is an increase of about 25% since Saturday.
AA spokesman Tony Rich said: “We advise drivers to adjust their speed to suit the conditions, especially when driving on wet or icy roads and to leave more room between their car and the one in front.”
