Snow and icy conditions will return on Monday night as the sunshine and double digit temperatures in some parts of the country are replaced by a reprise of the bitter winter cold of the runup to Christmas, according to the Met Office.
Yesterday, snow fell in Aberdeen, Glasgow and Edinburgh satisfying the official definition of a white Christmas. The coldest place in the country was Altnaharra in Scotland, which dropped below -18°C.
Michael Lawrence, a Met Office forecaster, said: "There's a more definite and widespread band coming eastward on Tuesday, so the cold weather will return very late Monday. Monday afternoon [the front] will be in western parts, but it will be mostly rain and sleet in that part of the world. As it progresses east it will fall into colder air and will more readily snow. We've just issued some flash warnings for Scotland."
"The conditions we've been having the settled conditions, the double figure temperatures look to be moving out of the way and they are being replaced by increasing southerly winds and fronts approaching from the west."
Warnings were issued again this morning for widespread icy roads and heavy snow across much of the UK, including the north, Yorkshire, London and the south, the Midlands, Wales and Scotland.
The Met Office website said: "There will be a continuing risk of widespread ice, affecting untreated surfaces in particular, as the cold weather continues. In addition, there is a continued risk of snow, heavy at times and accompanied by drifting in strong winds spreading erratically eastwards through the day. This snow may turn to rain in some western areas."
As shoppers hit the high street in search of bargains and workers began the slow return to work, the Met Office urged caution despite today's widespread sunshine and blue skies as roads remained icy.
Retailers are hoping for a Boxing Day boost, discounting heavily to lure shoppers into stores in an attempt to redress the pre-Christmas slump in sales, when footfall plummeted amid arctic temperatures and heavy snow.
Comparison website moneysupermarket.com predicted this year's Boxing Day sales could be the biggest ever, saying the UK is set to spend £323m online in a single day.
Selfridges is expecting 80,000 people to pass through the doors of its Oxford Street store, seeking discounts of up to 75%. A spokeswoman said: "Despite the fact we are opening at 11am due to Sunday trading, the first three shoppers started queuing at 11pm last night and by 4am there were 60 people waiting."
Consumers are expected to target bargains before the VAT increase from 17.5% to 20% on 4 January.
Shoppers coming into London also had to contend with a tube strike, which has affected most routes.
As for air travel, the transport secretary Philip Hammond told the Sunday Times that he wanted new regulatory powers after Heathrow ground to a standstill last week as hundreds of flights were cancelled and thousands of passengers had their Christmas plans ruined.
He said it was unacceptable that BAA, the company which runs the airport, would not be punished under the current scheme. "There should be an economic penalty for service failure," he said. "Greater weight needs to be given to performance and passenger satisfaction."
BAA today said it welcomed legislation that would "improve the experience for passengers". A spokesman added: "We will of course play a full part in the government's discussions about this year's weather disruption and will make public the findings of our own independent investigation."
Transport minister Theresa Villiers said the new legislation would give the regulator, the Civil Aviation Authority, greater powers to intervene between the regular five-yearly price reviews.
"The regulator would have the chance to get involved to work out whether the airport is performing well enough in the face of winter resilience, whether it has prepared well enough, and whether it has let passengers down or not," she told the BBC.
"It would give the regulator the power to fine an airport where it does let passengers down and doesn't prepare properly for severe weather conditions."