Forecasters have issued a rare red weather alert, warning that extreme snow and wind which could pose a risk to lives is heading to parts of Wales and south-west England.

The Met Office urged people in the affected area to take immediate action to keep themselves safe as Britain faces strong gales, blizzards and rare freezing rain.

And the sub-zero temperatures coupled with high demands for gas have led to fears of a shortage as the National Grid issued a “gas deficit warning” on Thursday morning.

The red snow warning, which begins at 3pm, is just the third issued in the past seven years and comes as Storm Emma blows in from the Atlantic.

It means “widespread damage, travel and power disruption and risk to life is likely”, with concerns some rural communities could be cut off for days.

The fresh warning comes after Scotland’s red alert ended at 10am.

A man tries to dig his car out of snow
A man tries to dig his car out of snow (Andrew Milligan/PA)

However, an amber warning, which still poses potential risks to life, is in force for much of the country until 10am on Friday.

Meanwhile, the Irish Republic was put under red alert at 11pm on Wednesday as it was hit by the worst snow in 35 years, with the warning set to run until 3pm on Friday.

Snowfall will grow heavier through Thursday afternoon and evening with 10-20cm likely to settle widely across red alert areas, Met Office chief meteorologist Paul Gundersen said.

He added freezing rain may batter parts of south-west England and Wales on Thursday night, potentially creating large, hazardous icy stretches as rain droplets supercool and freeze instantly upon hitting the ground.

Elsewhere, NHS England warned the current bout of freezing weather could increase health risks for vulnerable patients such as the very young, very old or those with chronic diseases.

A “perfect storm” of appalling weather, persistently high hospital admissions due to flu and a renewed spike in norovirus have put accident and emergency departments under considerable pressure, with the prolonged cold conditions set to put them under even more strain.

Meanwhile, thousands of children enjoyed a second snow day, with hundreds of schools forced to close their doors, including more than 125 schools in North Yorkshire, more than 330 across Kent and all schools and colleges in the Republic of Ireland.

Many forces warned motorists against driving unless absolutely essential, with Lincolnshire police saying travel on “most roads” was impossible.

Icy roads and poor visibility led to several crashes, with two collisions reported on the A34 in Hampshire on the south and northbound carriageways, closing both routes, South Central Ambulance service said.

It added the accident caused around seven to eight miles of trapped traffic.

Meanwhile snow ploughs are working to clear a miles-long tailback on the M62 between Rochdale and Huddersfield.

Cumbria Police said it was dealing with “multiple collisions”, including a jack-knifed lorry, and advised motorists to travel at 20 miles per hour, as Northumbria Police advised lorries travelling on the A1 to pull over.

The A52 was closed between Boston and Skegness all night, with not even a snowplough able to get through, the fire service said.

Highways England’s head of road safety, Richard Leonard, said: “Gritters are out treating our routes around the clock but it is still important to drive to the conditions when snow is forecast.

“If you need to travel in the morning, make sure you keep your distance and reduce your speed.”

Scotland has faced the brunt of the extreme weather so far, with police warning the public against travel until the severe amber warning passes at 6pm.

Hundreds of motorists on the M80 near Glasgow reported being stuck for up to 13 hours, with some spending the night in their cars, and others abandoning their vehicles.

Around 1,000 vehicles were at a standstill, tailing back eight miles in both directions, Police Scotland said.

Major airports including Manchester, London Gatwick and Heathrow told passengers that cancellations loomed, while Glasgow Airport announced it was closed until 3pm.

Rail services have also been mired by delays with Paddington Station announcing it will be closed from 8am due to severe weather conditions, halting Heathrow Express services.

Nearly all train operators across the UK are warning of cancellations and disruption, advising customers to check schedules before travelling.

More than a foot of snow was dumped in some parts of the country – peaking with 34cm of snow in Wittering, Cambridgeshire.

The Met Office said it had likely been deeper than this in some places, but dry, windy conditions had made it hard to measure.

Temperatures dipped as low as minus 10.3C in Kinloss, Scotland, overnight.