Britain was hit by unseasonal heavy snowfall on Friday that left tens of thousands of homes without power and forced the closure of a nuclear site.
Up to 40 centimetres (16 inches) of snow was expected in the worst-affected areas.
A spell of bad weather this month has seen British media dub it "Miserable March".
The Met Office national weather service said that while it was not unusual to see snow in March, the cold spell had been unusually long.
The government dismissed newspaper reports that gas stocks, drained by the ongoing wintry weather, were just days away from running out.
The Sellafield nuclear site on the northwest English coast was forced to close as a precaution due to the weather.
Staff were being sent home from the reprocessing and waste storage facility but there was no evidence of any safety issues, its operator said.
"In response to the current and predicted adverse weather conditions on and round the Sellafield site, as a precaution, a site incident has been declared and the plants have been moved safely to a controlled, shut down state," it said.
Sellafield was home to the world's first commercial nuclear power station, but it stopped generating electricity in 2003.
Across the Irish Sea, Northern Ireland bore the brunt of the snowfall, caused by cold westerly winds from Russia and northern Europe colliding with an area of low pressure moving eastwards off the Atlantic Ocean.
"40,000 customers are currently without power," said supplier Northern Ireland Electricity, which has reconnected around 50,000 properties restored following "storm force winds and blizzard conditions".
"Damage has been caused by flying debris and high winds, including broken electricity lines and damage to poles."
The snow forced the closure of Belfast City Airport, though the larger Belfast International remains open.
Northern Ireland's 2014 football World Cup qualifier with Russia was postponed until Saturday due to the snowy pitch at Belfast's Windsor Park.
More than 1,000 schools around Britain have been shut, while towns in Cornwall, southwest England, have witnessed flooding following torrential rain.
Temperatures were as low as minus 1.9 degrees Celsius (28.5 degrees Fahrenheit) in Dalwhinnie, central Scotland.
"We have had reports of around 15 centimetres of snow in Northern Ireland so far and similar levels over the Pennines (the spine of England) and into Wales," Met Office forecaster Helen Chivers told AFP.
"By the time it stops we're expecting to see up to 40 centimetres of snow in places.
"It's blowing around in the strong winds so there will be deeper drifts."
Consultancy JBC Energy said British gas storage levels had shrunk to just 10 percent of total capacity, according to data from operators' association Gas Storage Europe.
"UK natural gas prices have spiked to record levels this month as the country grapples with an emerging supply crisis," it added.
But the government played down press fears that Britain's gas stocks would soon run out.
An energy ministry spokeswoman insisted: "Protracted cold weather increases demand but the UK gas market is responsive and our gas needs are continuing to be met."
Weather conditions were forecast to improve over the weekend.