Snow shuts schools and hits travel
More than 5,000 schools were closed across the UK as snow and icy conditions continued for a fourth day.
Travel has also been affected, with disruption to road and rail journeys.
Gatwick's chief executive criticised Heathrow Airport after it cancelled more than 200 flights. He called for a "better way" to run London airports.
Snow is falling in northern England and southern and eastern Scotland, where the Met Office has amber "be prepared" warnings in force.
And the Environment Agency has issued one flood warning - meaning flooding is expected and immediate action is required - in Somerset, ahead of a "mix of snow, sleet or possibly rain" expected to hit south-west England on Monday evening.
Some 30 flood alerts are also in place across parts of northern and southern England, warning people to be prepared as "flooding is possible".
About one in six schools is thought to have been affected by the weather.
Education Secretary Michael Gove said "everything can and should be done" to keep schools open where possible.
He told MPs the government had made changes so no school which stayed open would be penalised if individual students could not make it to school on that day.
"And I hope as a result that more and more schools will recognise that, while the decision to remain open or closed is a matter for the headteacher, everything can and should be done in order to ensure that all children get access to a good education."
Forecasters say they expect 10-20cm (4-8in) of snow to fall during Monday in the "amber" areas - and even more on higher ground, with blizzard conditions in some areas. They are also warning of ice affecting East Anglia, southern England and south Wales.
Heathrow Airport said some 10% of the day's flights were expected to be cancelled, with "low visibility... forecast this evening".
The airport said there would be no pre-emptive cancellations on Tuesday, unlike the last few days.
However, cancellations and delays may still occur if problems result in cancelled flights at other international airports.
In other developments:
- It emerged a Somerset postman, John Bircham, is believed to have had a heart attack after trying to get his van out of a snow-drift in Exmoor on Saturday
- Thousands of schools across England have closed, including about 800 in East Anglia, 500 in the West Midlands, 600 in West Yorkshire, 120 in Northamptonshire and 100 in Surrey. Discussing the closures, the National Association of Head Teachers said heads had a duty of care to pupils
- In Wales, more than 120 schools closed - mostly in the south Wales valleys - and a new snow warning has been issued for south east Wales. Meanwhile in Scotland, a number of schools have closed mainly in the Borders and Aberdeenshire area and there are also closures in Northern Ireland
- A school bus with 20 children on board skidded off a steep road covered in slush and snow in Caerphilly, but no-one was injured in the incident
- Heavy drifting snow is causing problems in parts of Scotland, as forecasters warn of further snow and blizzards on higher ground
- On the rail network, there have been delays on a number of routes, with Greater Anglia, South West Trains, First Capital Connect, London Midland, Southern, East Coast, Virgin and Southeastern services reporting delays, and there are also revised services on the Gatwick Express, the Stansted Express and Eurostar
- Train services between Birmingham and Cheltenham have been suspended due to a line blockage, with southbound trains being returned to Birmingham
- Heavy snowfall has led to the closure of a number of main roads, including the A169 in North Yorkshire and the A66 in Cumbria
- A woman has died after she was found collapsed in the snow in Kent on Sunday
- A 16-year-old boy is critically ill in hospital after he hit a tree while sledging on Teesside on Sunday
- Tributes have been paid to climbers who died in an avalanche in the Scottish Highlands on Saturday, meanwhile a fourth victim has been named
- The Army was called in to help when two buses got stuck in snow in Northumberland, leaving passengers stranded for hours
Gatwick Airport has criticised the number of "pre-emptive flight cancellations at Heathrow", due to what it calls "small amounts of snow", and called for a "better way" to run London airports.
The airport's chief executive, Stewart Wingate, said: "I am proposing that for the key winter months of December, January and February, Heathrow declares a level of capacity it can cope with in winter conditions. The additional flights then, for those three months, can move to Gatwick and Stansted.
"As a result there would be better use of the existing capacity at our London airports, safety would be enhanced and passengers will not have to panic every time it snows. London's and the UK's reputation is on the line and the airports should work together to make this happen."
In response, Heathrow - which had 202 cancellations on Monday - said the Airports Commission had been set up by ministers to examine the issues of UK airport capacity and it was "for the commission to make recommendations for how the shortage of UK hub capacity should be addressed and to consider all options".
Other airports, including Gatwick and Birmingham, have also experienced disruption to flights, while flights at Leeds Bradford Airport remain disrupted.
The Met Office also issued yellow "be aware" snow and ice warnings for parts of Scotland, Northern Ireland, Wales, the East Midlands, the east of England, south-west England, London and south-east England.
It says persistent snow will continue to affect much of eastern Scotland for the rest of Monday and Tuesday. However, snowfalls in other areas should ease by late Monday, it says.
The latest weather update is valid until 15:00 GMT on Tuesday.
In most parts of the UK temperatures are lingering at about 0-2C.
Forecasters say an area of wet weather due to hit south-west England later could cause further icy conditions when rain and sleet hits frozen ground as it moves across southern England.
The Met Office warned that the public should be prepared for the risk of further disruption to travel, and the likelihood of road closures, as well as possible disruption to power supplies.
Meanwhile, the Highways Agency says main roads should be clear of snow.
Later on in the week, the BBC Weather Centre forecasts further sleet and snow at times, with widespread frost and ice likely.