The UK experienced its coldest January night in 15 years after a hamlet in northern Scotland dropped to minus 17.3C on Friday.
Altnaharra, which is in the most northern region of the Highlands, reached the temperature shortly before 8pm, the Met Office said.
It is the coldest January overnight temperature since 2010, when temperatures dropped below minus 15C several times at locations across the UK, including minus 22.3C on January 8 in Altnaharra.
Forecasters said they are not expecting temperatures in the Sutherland hamlet to fall below minus 18C on Friday but there is a very small probability it could reach 19C.
Altnaharra reached minus 14.5C on Thursday night.
Temperatures for large parts of the UK are set to fall again as the cold weather continues.
Met Office meteorologist Alex Deakin said: “Friday night into Saturday morning may well be the nadir of this current cold spell.”
Towns and cities in Scotland could see minus 2C to minus 5C and the Highlands may reach minus 14C or minus 15C.
Higher ground in England such as the Pennines could hit minus 11C or minus 12C while the coldest city in England is expected to be Birmingham, which may reach minus 4C.
The average low in northern Scotland for this time of year is about 0.3C, while for England, overnight lows are around 1.5C to 1.6C.
Met Office meteorologist Zoe Hutin said: “Certainly a cold night to come, especially for those beneath clear skies in the east and the north and in rural spots as well.”
Cloud coverage is keeping the temperatures from falling as low but it will still be chilly, Ms Hutin said.
Snow may fall overnight in hills of the south-west and parts of Northern Ireland but not to the same level as the past 10 days.
Saturday is forecast to be cold too, and Ms Hutin said: “We’ve still got tonight to come, and tomorrow night could also be chilly as well.
“Temperatures for tomorrow night, it will be mainly eastern parts that see temperatures dropping widely below freezing, so East Anglia, the north-east of England, northern and eastern Scotland as well.
“So another chilly night to come on Saturday, but then as we go into Sunday and into Monday, then we can start to expect temperatures to recover somewhat.
“I won’t rule out the risk of seeing something around or just below freezing again on Sunday night into Monday, but it won’t be quite so dramatic as the temperatures that we’re going to experience as we go overnight tonight.”
Looking ahead to next week, she said: “We’re saying it’s getting milder but by no stretch does that mean (temperatures) are going to be above average – it just will feel comparatively much more pleasant than it is at the moment.”
The UK has experienced a “particularly long cold spell”, she said, adding: “It has been getting progressively colder each night this week, whereas looking at previous years, we’ve had maybe two or three days where things have been particularly cold.”
