Further travel disruption is expected this week with temperatures forecast to stay well below freezing overnight, and up to 10cm of snow forecast in the south-east of England.
Met Office yellow warnings were in place from Sunday until Monday morning for northern and south-western Scotland, Northern Ireland, north-eastern England, the Midlands and south-west as well as London and the south-east.
Rail travellers in the south-west of England were told to expect delays, revisions and cancellations on Monday, after train operator South Western cancelled numerous services on Sunday because of icy conditions.
Airports were also being affected, with both Gatwick and Stansted having to close their runways to clear snow on Sunday.
Flights from Stansted were suspended. The airport released a statement saying “passengers are advised to check with their airline for current status of their flights.”
Gatwick issued an update on Twitter, saying, “snow and freezing weather may cause disruption at the airport. Passengers are advised to check flight status with their airline – and also local travel conditions – before departing”.
Elsewhere, National Highways advised road users in the south-east not to travel unless essential.
The organisation said Kent was particularly affected, with snow severely impacting the M2, the M20 around junctions 8 and 9, the A21 and the A249
The railway line between Dover and Minster via Deal was closed on Sunday after ice prevented trains getting electricity from the conductor rail, which powers locomotives. The same problem caused major disruption on the line from Lewes and Seaford to Eastbourne and Hastings in Sussex, Southern said.
Residents in Cornwall were being advised not to travel on Sunday or Monday because of the treacherous weather. The Cornwall fire and rescue service control centre dealt with more than 300 reports of road traffic accidents linked to ice over the weekend.
With temperatures in the county expected to plummet to -7C overnight on Sunday, residents were being asked to avoid travel unless essential and parents and carers were warned that schools could be closed.
At least 30 flights from Heathrow were cancelled on Sunday morning as freezing fog blanketed London – with snow and ice likely to cause further problems for Monday rush-hour travellers.
Snow in Sheffield brought further misery to hundreds of people in the Stannington area, who have been without gas since 2 December after water flooded into gas pipes.
Heavy snow in the Midlands caused sporting and festive events to be cancelled, including the Victorian Christmas market in Stratford-upon-Avon. Emergency services were called to Solihull, where police said four children were in a critical condition after being pulled from a lake in the freezing temperatures.
The Met Office warned that the cold weather was set to continue. The meteorologist Rachel Ayers said: “We could see 2cm to 5cm [of snow], perhaps up to 10cm in some places, with Kent and Sussex most affected, with areas most exposed such as North and South Downs and higher ground going to see the more significant accumulations.
Ayers said that although cold temperatures, freezing fog and wintry showers were expected through the week, cloud cover could prevent some of the more extreme temperatures experienced in recent days.
She added that there was a possibility of slightly milder conditions arriving next weekend but it was too early to be certain.
The Met Office said there is a small chance of some rural communities becoming cut off along with a possibility of power cuts and mobile phone coverage being affected.
Elsewhere, the UK Health Security Agency sent out a level 3 cold weather alert covering England until Friday, having extended the alert from Monday.
The agency is advising people to look out for friends and family who are vulnerable in the cold and to ensure they have access to warm food and drinks, adding that people should maintain indoor temperatures of at least 18C (64.4F).
The AA advised motorists to adjust their driving speeds in light of the freezing conditions, and to leave plenty of space behind other vehicles.
The recent cold snap has led to the triggering of the £25 cold weather payment to people on the lowest incomes in hundreds of affected postcode districts in England and Wales.
The government payments are given to eligible households in areas where the average temperature has been recorded, or forecast to be, 0C or below for seven consecutive days.
