Temperatures are set to plummet as low as minus 8C, the coldest of the winter so far.
Parts of England were still subject to ice and snow warnings, and the Met Office said further alerts are likely to be issued as the week goes on.
The mercury is set to drop sharply, with lows of minus 15C possible in Scotland and northern England overnight on Thursday and sub-zero temperatures expected across the country.
In Blackburn, temperatures are set to reach lows of minus six whilst in Rossendale, temperatures are forecast to plummet to minus five. It will be a similar temperature in Accrington.
The rural areas are where the temperatures will be really plummet.The Ribble Valley’s temperatures are forecast to hit minus nine says the Met Office.
The coldest forecast temperatures are set to hit parts of Pendle, where temperatures overnight in Colne could be down to minus 8C but could feel like minus 12C.
Bacup temperatures will plunge to minus 6 but it could feel like minus 11.
A Met Office forecast for the night says: “Largely dry with a few showers along the coast during the early hours. Elsewhere, very cold under the clear skies with a severe frost, icy stretches and some freezing fog. Minimum temperature -8 °C.”
The UK Health Security Agency (UKHSA) has extended its cold weather health alert for all of England until Sunday.
Amber alerts issued on Thursday have been extended and will now run until January 12, meaning a rise in deaths is likely, the agency said.
Dr Agostinho Sousa, head of extreme events and health protection at UKHSA, said: “We are extending the duration of our Cold-Health Alert, since the Met Office are forecasting that the low temperatures we are seeing will continue further into this week, with snow and icy conditions likely to persist.
“This weather can have a serious impact on the health of some people, including those aged 65 and over and those with pre-existing health conditions, and it is therefore vital that we continue to check in on friends, family and neighbours that are most vulnerable.
“These people could be more at risk of heart attacks, stroke and chest infections as a result of cold temperatures.”