Temperatures in Altnaharra, Sutherland, plummeted to minus 14.5C overnight, making it the chilliest night of the winter so far in the UK.
Friday night is expected to see the coldest temperatures of the current cold snap, with projections ranging between minus 15C and minus 20C in parts of Scotland and northern England.
This was the coldest January overnight since 2010, which saw temperatures fall below minus 15C multiple times, including a record low of minus 22.3C on January 8 in Altnaharra.
Most of Wales, Northern Ireland, and large parts of eastern England were under ice warnings until 10am on Friday.
The Met Office noted that Friday will mark the “start of a change to our weather,” with milder temperatures trying to move in from the south-west, but making “limited progress.”
This will result in patchy rain, sleet, and snow across parts of south-west Britain.
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Oli Claydon, a spokesperson for the Met Office, said: “It will be another cold night tonight with temperatures as low as minus 15C again in the Scottish Highlands.
“There’s a chance we could even see the coldest night of winter again.”
Motorists are being urged to stick to major roads that are most likely to have been gritted.
Alice Simpson, spokesperson for the RAC, said this week had been “one of our busiest for breakdowns in the five years since the Covid-19 pandemic.”
She added: “Until the weather warms up on Sunday, there is an ongoing risk of ice and snow which will make the roads treacherous.”
Snow and winds have also led to rail disruptions, with some lines forced to close.
National Rail reported on Friday morning that some Southeastern services to and from London and Charing Cross were affected by ice.
Hundreds of schools in Scotland, and around 90 in Wales, were shut on Thursday.
The UK Health Security Agency (UKHSA) has extended its cold weather health alert for all of England until Sunday.