Temperatures widely dropped to between -1C (30.2F) and -4C (24.8F) across the UK on Wednesday morning, getting as low as -7.8C the Grampians, Scotland, and -7C in Shap, Cumbria.
Further heavy snow fell in northern Scotland overnight, while north Wales and the midlands also woke up to fresh snow on the ground.
Yellow weather warnings were in place for parts of all UK nations early on Wednesday, signalling likely disruption to travel and a danger of slips and falls on icy ground.
A new warning for ice will kick in at 16:00 for most of Scotland as well as much of mid and north Wales, Northern Ireland, the West Midlands, the north of England and Northern Ireland.
This will last until 10:00 on Thursday.
Parts of northern Scotland and its west coast are covered by snow and ice warnings until 12:00 on Thursday.
Meanwhile, a yellow warning for snow will come into force in much of South West England at 05:00 on Thursday, lasting until 15:00.
On Wednesday, nearly 100 schools and nurseries were shut in Scotland as well as almost 50 in Wales and at least 30 in England due to frosty conditions.
Commuters were advised to plan ahead and take extra care while driving.
In Cornwall, a person was taken to hospital after a four-vehicle crash in icy conditions, police said.
Elsewhere in Aberdeenshire, a bus ended up on its side in icy road conditions in the New Leeds area on Tuesday. There were no injuries.
The RAC said it had seen a sharp rise in breakdowns, mostly due to people’s batteries failing in the cold.
It urged drivers to travel prepared for a breakdown.
“A blanket, warm waterproof coat and gloves, sturdy footwear and a charging cable and mobile power bank are all essentials,” said spokeswoman Alice Simpson.
Transport for Wales said 13% of its rail services had been disrupted by severe weather, while crashes were reported on snowy roads.
In north Wales, trains were suspended between Llandudno and Blaenau Ffestiniog until about 07:30 on Wednesday, while a road in Wrexham was blocked by a lorry stuck in snow.
Northern Ireland avoided the worst of the snow, but Translink warned of disruption to some services in the Magherafelt and Cookstown areas, including school routes, due to road conditions.
ScotRail said it was struggling to source rail replacement transport due to the weather, after a fallen tree caused disruption to some services in and out of Aberdeen – but tickets were valid on existing Stagecoach North services.
A raft of services were disrupted on the Mersyrail train network, while road disruptions were reported in parts of North Yorkshire.
