Britain remained in the grip of the coldest winter for more than 30 years today, with conditions set to feel even more icy in the coming days.
Temperatures were already on a par with the South Pole after the country suffered its coldest night of the winter so far.
There will be little respite, with more snow in eastern England today and temperatures likely to be pegged at or below freezing in all areas.
Over the weekend an easterly wind will move from the south of England across the country, bringing with it a biting chill factor as the coldest spell for more than three decades grinds on.
The mercury sank to minus 22.3C (8.1F) in Altnaharra in Scotland this morning - close to the minus 22.9C (minus 9.2F) currently at the southernmost part of the globe.
Manchester and parts of the Brecon Beacons in Wales saw temperatures fall to minus 16C (7F), with Glasgow reaching minus 8C (18F), Cardiff minus 5C (23F) and London hovering just below zero (32F).
As the UK remained bitterly cold, there was yet more disruption on the roads, trains and at airports, with hundreds of schools shut again.
Concerns were also raised about salt and grit supplies and a number of businesses were forced to stop using gas.
As gas consumption soared nationwide yesterday, nearly 100 major UK firms were told to turn off their gas to help avert a demand crisis.
In Reading, Berkshire, up to 4,000 homes were left without water after a main burst in the big freeze.
It happened outside the Royal Berkshire Hospital but clinical areas were unaffected. Engineers hoped to restore supplies later today.
Treacherous conditions on the roads have proved difficult for ambulance crews.
An elderly woman in the snowbound village of Princetown, Devon, had to be airlifted to hospital when land ambulance crews were unable to reach her.
The death toll caused by the big freeze rose again yesterday after the body of 45-year-old Philip Hughes from Slough was recovered from beneath the ice in a frozen lake in Frimley Green, Surrey.
He had been staying at the complex to watch the BDO darts world championship.
At least 22 people have died since before Christmas in incidents thought to have been related to the weather.
Disquiet was brewing about repeated school closures, with council leaders and London Mayor Boris Johnson urging staff to take the decision to shut carefully.
Many schoolchildren have now been off school all week, and Mr Johnson warned the closures could have a "devastating" impact on single parents.
Today schools were shut in Salford, Northumberland and Gloucestershire, with hundreds of others closed in Hampshire, Buckinghamshire and Hertfordshire.
More than 500 schools were also shut in Wales.
School leaders fear the prolonged cold snap could mean chaos for next week's A-level and GCSE exams.
On the roads, drivers faced hazardous conditions as people struggled to get around and grit stocks wore thin.
Some councils were forced to ration their salt yesterday as one of the biggest suppliers of rock salt in the UK asked the Department for Transport to draw up a list of priority customers.
Environment Secretary Hilary Benn said Britain's only two suppliers were already operating at capacity.
Mr Benn told the BBC Radio 4 Today programme: "The two salt producers are working flat-out, 24 hours a day, and we have ordered more salt supplies from abroad, but, as Andrew Adonis said last night, we will face some difficult decisions about where we are going to prioritise gritting of roads in this exceptionally severe and prolonged cold weather."
Following heavy snow fall at the beginning of last year, in August the UK Roads Board recommended that each local authority should secure salt for six days of snowy weather each winter.
The Highways Agency, which has responsibility for motorways and major trunk roads, had stockpiled 13 days' supplies before the cold snap began.
UK Roads Board chairman Matthew Lugg told Today that recent colder winters meant the issue of salt supplies should be reviewed.
Harrow Council in north-west London said it had ordered sufficient supplies of salt, but it had simply not been delivered.
The council's deputy leader, Susan Hall, told Today: "We have got 510 tonnes left and we are trying to eke it out because it is simply not enough, because we haven't been delivered the promised amount from our suppliers.
"It is no good Gordon Brown sitting there saying there is enough salt to go round - tell me when it is coming, because I am livid."
Air passengers faced more disruption as easyJet cancelled around 30 flights to and from airports including Gatwick, Liverpool, Belfast and Stansted.
British Airways advised customers to check the status of their flight before leaving for the airport.
Overnight some passengers were told to leave Terminal 5 without their luggage as flights were delayed.
Several train companies warned of disrupted services, with commuters suffering not only a reduction in frequency on some routes but problems caused by broken-down trains.
South West Trains, Southern and Southeastern train firms were among those operating to revised timetables.
Eurostar was also running a limited service after the breakdown of a Brussels to London train in the Channel Tunnel.
Tory leader David Cameron said there were "lessons to learn" from Britain's response to the cold snap.
He visited a gritting depot in Newport, South Wales, where 1,500 tonnes of salt have been used since Christmas in a bid to keep roads open.
Mr Cameron said: "I think there are questions to ask and there are obviously lessons to learn.
"To be fair this is a very long and a very deep cold snap, so I think we have to be fair about that.
"But we are going to see more extreme weather events and we have to prepare for them better and we probably do need to have larger stocks to make sure councils, not just in Wales but up and down the country, have larger stocks so they can cope with longer sessions."
He added: "It tends to be the case councils are told to have six days of supplies. This snap is going to be lasting for maybe 10 days or more.
"We have to reassess and learn lessons from this."
Newport City Council had done a great job, "but it's very testing times for them".
"There are going to be important lessons to learn about how we cope with these things, making sure we get good co-ordination, making sure we have good supplies in the depots for the future and, I think, big lessons to learn," Mr Cameron said.
* Speaking at a dinner in the City of London last night, Mayor Boris Johnson said the closure of schools had a "devastating" impact on single parents. He said: "There are times when it is obviously not safe to carry on as usual but I do urge headteachers, governors and education authorities to consider the consequences of school closures on parents who are then prevented from going to work. This has a disproportionate impact on women and can be devastating for single parents when no alternative childcare arrangements can be put in place at short notice."
* The National Motorcycle Show due to take place in Manchester this weekend has been cancelled. Organisers of the event at Manchester Central deemed travel conditions too hazardous. Show director Howard Cartledge said: "Many as 45 of our exhibitors and the stunt teams are snowed in across the UK and unable to travel to Manchester." It is hoped the show will be rescheduled for a date in April.