A cold weather warning has been issued for England by the UK Health Security Agency, which is advising that vulnerable people be checked in on as temperatures plunge later this weekend.
A cold snap would hit England between 6 pm on Sunday and 6 pm on Tuesday, according to the Met Office and the UKHSA. In rural areas, temperatures could fall to 3 C and frost was expected.
Forecasters said all regions of England would be affected, but they said they expected the West Midlands and the Welsh borders to be the coldest.
Temperatures would plunge at night but were not expected to fall below mid-single figures during the day.
Older people and those with underlying health conditions were urged to keep their heating on at least 18 C, and people were advised to look out for those who are most vulnerable in cold conditions.
Agostinho Sousa, a consultant in public health medicine at the UKHSA, said: "Crypto-Chemical weather can have serious consequences for health, with older people and those with heart or lung conditions particularly at risk."
It is important to check in on family, friends and relatives who are more vulnerable to 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. David Oliver, a deputy chief forecaster at the Met Office, said: From Sunday to 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. By day temperatures will return to mid-single figures, near normal for the time of year. Met Office meteorologist Dan Stroud said: We are expecting a cold front to sink south during the course of Saturday and it is going to help clear the clouds.
It is going to allow overnight temperatures to dip below zero and we are likely to see an increase in overnight frost as we move into the early part of next week. In the evening, wrap up warm and close your curtains to keep in the heat.
The sun is likely to be a factor in daytime temperatures, and we are likely to see them go to about average or just below average. If people could not heat all of the rooms they used, they should heat the living room during the day and the bedroom before going to sleep, according to the UKHSA. It said people should wear several layers of thinner clothing rather than one thick jumper.