Brits are being urged to crank up the heating after a cold weather alert was issued for England and more snow expected.
Families are encouraged to heat their homes to 18°C in a bid to stay warm amid possible snow and subzero temperatures, according to the UK Health Security Agency (UKHSA).
The advice comes as millions struggle to pay their energy bills while Shell profits soared to £32.2billion ($39.9billion) last year - the highest in its 115-year history.
Plummeting temperatures and overnight frosts are expected to hit all regions across England from 6pm on Sunday until 6pm on Tuesday, the Met Office and UKHSA said.
Much of the country has been able to enjoy relatively dry and mild weather of late, with overnight temperatures as high as 10C in London on Friday.
But this is set to change with long clear spells overnight bringing temperatures down to below freezing, with frost spreading across the country.
The mercury is likely to creep back up during the day to near average for the time of year, but plummet suddenly when evening settles in.
However, Brits may be pleased to hear that they can at least leave their umbrellas at the door during the big freeze with no rain on the cards.
Dr Agostinho Sousa, consultant in public health medicine at UKHSA, said: “Cold weather can have serious consequences for health, with older people and those with heart or lung conditions particularly at risk.
“It’s important to check in on family, friends and relatives who are more vulnerable to the cold weather.
"If you have a pre-existing medical condition or are over the age of 65, it is important to try and heat your home to at least 18°C if you can."
Residents who cannot afford to heat all the rooms they use should heat their living room during the day and the bedroom just before going to sleep, according to government advice.
Wearing several layers of thinner clothing will keep you warmer than wearing just one thicker layer.
Having plenty of hot food and drinks is also effective for keeping warm, it adds.
David Oliver, Deputy Chief forecaster at the Met Office, said: “From Sunday and into early next week an area of high pressure will dominate the UK’s weather.
"This will bring some cold nights with a widespread frost across the country. However, by day temperatures will recover to around mid-single figures, near normal for the time of year.”
Brits can check the latest advice on the risks of cold weather and tips for staying warm this winter via the UKHSA supplemented cold weather plan for England.
Those struggling to afford their heating bills can access free advice on energy efficiency and national grants via the Simple Energy Advice service.