Disruption to airports and traffic networks is expected to continue today as another round of snow sweeps across the UK.
Up to 10cms is expected to fall this morning in parts of Scotland and northern England and a further 2cms in East Anglia, followed by around 6cms in southern England this evening, forecasters have predicted.
The heavy snow and frost have so far claimed the lives of seven people, including a postman who Royal Mail last night confirmed died while carrying out his rounds during the weekend's freezing temperatures.
John Bircham died on Saturday during his collection on Exmoor, Somerset, after 25 years of service as a postman.
A 25-year-old woman died after collapsing in the snow on her way home in sub-zero temperatures following a night out.
Bernadette Lee was discovered in the front garden of the house next to her sister's by a man walking his dog on Sunday at 7.30am in Church Meadows, Deal, Kent.
Kent Police are investigating the cause of death but there are reports she had no visible injuries and was found without a coat.
A man was killed in another weather-related incident when the car he was driving left the road and crashed into a tree on the A12 in Essex last night.
It comes after four people died in an avalanche as they descended Bidean Nam Bian in Glencoe on Saturday afternoon. A further two people survived.
Elsewhere, a teenager remains critically ill in hospital after being injured while sledging in Middlesbrough.
Overnight temperatures plummeted to as low as -11.3 in Buckinghamshire, -10 at Stansted Airport and -9 at RAF Mildenhall in Suffolk.
Heathrow Airport has already warned passengers to expect cancellations and delays today and Gatwick has also advertised delays on its website.
More than 200 flights were cancelled at Heathrow Airport yesterday, while other airports including Gatwick and Birmingham also experienced disruption.
The wintry conditions saw Robin Hood Airport near Doncaster closed, along with the runway at East Midlands Airport. Leeds Bradford Airport was also closed for a short period while snow was cleared.
Passengers were advised to check the status of their flights before travelling.
A Heathrow spokesman said: "Because Heathrow runs at almost 100% capacity there is no slack in the system and flights unfortunately have to be cancelled. Further cancellations are inevitable given the adverse weather conditions at other airports around Europe."
A forecaster for MeteoGroup said: "With more snow coming today, we can expect more disruption.
"This morning we will see up to 10cm in snow in Scotland, northern England and around 2cm in East Anglia followed by more snow this evening in southern England - maybe up to 6cm.
"Temperatures were very low overnight, as low as -11.3 in Buckinghamshire, and will be low again tonight with many places struggling to stay above freezing during the day.
"The rest of the week will see widespread frost and showers."
Trains were also affected by the severe weather yesterday with many services cancelled, and the heavy snow closed two major roads across the Pennines.
The cold weather led to thousands of children having an extra day off as hundreds of schools remained closed. In some cases, parents were asked to bring shovels to help clear paths to enable them to open.
Teenager Liam Stafford remains critically ill in hospital after hitting a tree while sledging in Flatts Lane Country Park, Normanby, Middlesbrough, at 1pm yesterday.
The 16-year-old was flown by the Great North East Air Ambulance to the James Cook University Hospital in Middlesbrough suffering from head injuries.
East of England Ambulance Service also issued a warning after it was called out to attend at least a dozen sledging-related injuries.
While none was life-threatening, some children and adults sustained broken bones or head injuries requiring hospital treatment.
Another warning was given by London Fire Brigade, which told people to stay off the ice after being called to rescue two men who had fallen through frozen lakes to rescue their dog yesterday. Crews also rescued a child who was stuck on his sledge in the middle of a frozen lake.
The Met Office has issued severe weather warnings as rain falling on to frozen surfaces increases the risk of ice.
Amber warnings remain in place for heavy snow across the higher ground of north-east England and eastern Scotland while yellow warnings are in place for ice and snow across parts of South Wales and western England.
The AA said it was expecting today to be one of the busiest days for call-outs this winter, at more than 17,000.
Breakdowns were being reported at a rate of around 2,000 an hour with the busiest areas being the Midlands, London, the South West and the South East.
Speaking as he signed a memorial book to commemorate the lives of those killed in the Holocaust, David Cameron said he expected his youngest daughter, Florence, to make a snowman.
Discussing the snow that had settled in London, he said: "You never normally see, after a few days, the snow still on the trees.
"I was just talking to my two-year-old daughter and said that she has got to make a snowman this afternoon, while it's all still there ... the first time they see snow is an exciting moment."
Emergency services in Devon were called to a serious crash this morning after several vehicles spun off the main route into Plymouth.
At least one person is seriously ill in the city's Derriford Hospital following the collision on the A38 between the Manadon and Marsh Mills junctions of the Exeter-bound carriageway shortly before 6am.
The road has been closed at the sliproads joining at Devonport and St Budeaux. The Exeter-bound carriageway is open from the Tamar Bridge but traffic is being directed off at St Budeaux, police said.
A Devon and Cornwall Police spokesman said: "Diversions have been set up but there will be inevitable delays for the rush-hour traffic.
"Officers at the scene believe that the freezing road conditions may be a contributory factor and are warning motorists to slow down when using any of the roads in the area.
"Further collisions on the approach to the scene are also adding to the congestion and motorists are advised to delay journeys or avoid the area if possible."
Large pockets of Cornwall experienced their first snow-based disruption of 2013 today, as many awoke to a thin layer.
The far south west of England had been left largely untouched as the rest of the country saw roads blocked, schools and businesses closed, and streets turned into makeshift ice rinks as winter tightened its icy grip last week.
But today many parts of Cornwall reported snowfall overnight, with Cornwall Council announcing that several schools had delayed opening times to allow the roads to thaw and giving teachers, staff and pupils safe access to the grounds.
A handful of schools in the exposed Bodmin Moor area of the county decided against opening at all, as reports of ungritted rural roads made it difficult for people to get in.
Snow continued to disrupt work and travel across Wales today, with several hundred school closures and the south east hardest hit.
In the Caerphilly Council area, a total of 91 schools were reported shut today due to the adverse weather.
Just five schools are listed as open. They are: The Twyn School, St Helens Catholic Primary, Deri Primary, Cwm Ifor Primary, Coed-y-Brain Primary.
In the Rhondda Cynon Taf council area, 91 schools are reported closed after snow and freezing conditions overnight.
The county has seen close to a three-fold rise in school closures today, after only 33 shut yesterday.
In Torfaen, which covers towns such as Pontypool and Cwmbran, a total of 33 schools were reported closed at 9am today.
In the Merthyr Tydfil County Borough Council area, there were 31 school closures and in the Blaenau Gwent council area, 33 schools reported closed together with Coleg Gwent's Ebbw Vale Campus.
Snow overnight across the Cardiff Council area has meant that 56 schools are shut today.
Bridgend County Borough Council has 15 schools reported closed.
Adverse weather continues to affect some roads with the A4107, Bwlch Mountain Road closed in both directions.
The A4233 Maerdy Mountain Road is also closed in both directions as are the Caerphilly and Rhigos mountain roads.
The Traffic Wales pan principality website was reporting this morning that: "All other major trunk roads are passable with care."
Snow is already falling on eastern and western parts of the principality, with many areas waking to sub-zero temperatures.
Icy conditions forced the temporary closure of the northbound A38(M) Aston Expressway, which links Birmingham city centre with the M6, during the morning rush-hour.
At least 26 schools remained closed in Walsall, as well as 43 in Birmingham, while a total of 39 schools stayed shut in Dudley Borough, Wolverhampton and Staffordshire.
Some schools cited unsafe conditions on surrounding roads as the reason for deciding to close, while others fell victim to on-site ice or problems with heating systems.