Temperatures have stayed firmly below freezing for the 12th night in a row across the UK, as forecasters predict the weather will turn milder into next week.

Scotland remained the coldest place in the UK, with the Met Office reporting a low of -13.9C (7F) in Kinbrace in the northern Highlands. Wales experienced a low of -2.2C in Hawarden, Flintshire; England’s coldest temperature was -7.8C at Cavendish, Suffolk; and Northern Ireland recorded -1.5C at Katesbridge, Co Down.

Greater London had temperatures of -6.2C, with it being -2.6C in the centre of the capital. Edinburgh reached a low of -1.7C, while Cardiff hit a comparatively balmy 3.2C, according to the forecaster’s data.

It means that the UK as a whole has not had temperatures go above freezing at night since the year began, and the last time the temperatures were in positive figures was on New Year’s Eve.

Jonathan Vautrey, a Met Office meteorologist, said it would feel considerably warmer in the early stages of next week, caused by southerly winds bringing warmer air.

Another meteorologist at the Met Office, Greg Dewhurst, said that by Monday morning, Northern Ireland and western Scotland could have temperatures of between 9C and 10C. Most places would be between -1C and 3C, he added, warmer than recent nights.

Next week is expected to start with a north-south split in terms of temperatures and wider weather. Northern Ireland and the northern half of the UK are forecast to be cloudy with outbreaks of patchy rain and temperatures between 9C and 12C, while central and southern areas could be drier, with temperatures between 5C and 8C.

Tuesday will be similar, but potentially drier, with temperatures between 11C and 12C in the north and 8-9C in the south.

A Met Office spokesperson said: “Daytime temperatures for the week ahead will typically be 9C to 12C by day and frost generally limited to central and southern counties of England and Wales at night with minimums around 2C to -2C.”

Vautrey said warmer temperatures could lead to thawing snow and surface water on roads.

Scotland and Northern Ireland are forecast to experience rain on Sunday night into Monday morning. Northern Ireland, north-west England and western Scotland could have strong winds, brought by the low pressure weather system moving in from the Atlantic.

The winds could be “severe” for the Outer Hebrides and the highlands, Vautrey said.

An amber cold weather health alert is in place from the UK Health Security Agency until 9am on Tuesday morning. The alert says a rise in deaths, particularly among those aged 65 and over or with health conditions, is likely.

Flood alerts are in place for England from the Environment Agency, and in Scotland from the Scottish Environment Protection Agency.

Friday night brought the coldest January overnight temperature since 2010. Altnaharra, a hamlet in the Scottish Highlands, recorded -18.9C. Shap in Cumbria had reached -11C, and Heathrow registered -5C.

The increased demand on energy supplies caused by the cold snap meant the government was forced to insist the UK had enough gas and electricity stocks to meet demand, after the owner of the country’s largest gas stores said levels had become “concerningly low”.