More snow and ice forecast for UK in coming week
Roads were closed over the weekend and more snow is forecast
Forecasters say there will be no let up in the wintry weather affecting the UK, with more snow and sub-zero temperatures likely in the coming week.
Met Office warnings are in place for widespread ice across many regions.
More snow is also set to spread across the UK and BBC forecaster Peter Gibbs said few, if any, areas would escape.
The Scottish Government has said it does have enough salt and grit to cope, despite claims from some councils that supplies are running out.
The Met Office has issued severe weather warnings for heavy snow and ice in the Highlands and Eilean Siar, Grampian, Aberdeenshire and Moray on Monday, with up to 10cm (3.9in) possible.
There are further warnings of widespread ice in Orkney and Shetland and Northern Ireland.
BBC forecaster Peter Gibbs said he could see no end to the freezing conditions for at least a week.
"It's going to stay cold and perhaps get even colder in parts," he said. "There probably won't be many places that don't see some snow by the end of the week.
We're going to start seeing a very cold easterly wind feeding in direct from Siberia
Peter Gibbs
BBC forecaster
Grit supplies 'not running out'
"At the moment, the whole of northern Britain is really plastered in snow and temperatures fell to -12C overnight in the Highlands, -11C in parts of Wales.
"It's also going to be extremely icy on Tuesday morning for many of us, so really very difficult conditions for drivers and the authorities to cope with."
He added: "We can see no let up. By the weekend we're going to start seeing a very cold easterly wind feeding in direct from Siberia."
Met Office advisory warnings of possible heavy snow are in place for Tuesday, Wednesday and Thursday in northern and eastern England and Scotland.
'Pinch points'
The freeze, combined with rail delays, led to disruption for people returning to work on Monday morning after the Christmas break.
Trains in and out of London's Liverpool Street station were delayed for up to 60 minutes by over-running engineering work and services between Glasgow and Edinburgh were also interrupted by poor weather.
By 0800 GMT on Monday, the AA said it had attended about 6,000 breakdowns since midnight, with a total of more than 22,000 expected by the end of the day.
The motoring organisation said that was about two-and-a-half times more than on an average Monday, with many call-outs prompted by flat batteries, frozen engines, or accidents on icy roads.
Up to 9cm of snow was recorded in Edinburgh on Sunday
Meanwhile, Bob McLellan, head of transportation services at Fife Council, said that after Monday morning's "pre-grit", supplies of salt had "effectively run out".
Renfrewshire Council also said there would be significant problems if stocks were not replenished.
But Scottish Finance Secretary John Swinney insisted there was a "very substantial" amount of salt and grit available.
"There will be pinch points in different parts of the country because of issues around about delivery," he told the BBC.
"There's a lot of supply around. We just have to make sure its in the right places."
Paul Watters, from the AA, said the salt and grit supply chain was "creaking a bit" because the cold snap had been so prolonged.
"Obviously, the priority has to be the main routes - the routes to hospitals, bus routes - and the pavements, because there are a lot of [bone] fractures at the moment [among] pedestrians who slip over.
"The small routes obviously can't take priority in these circumstances."
