Sub-zero temperatures made Saturday night the coldest so far but forecasters say the big freeze will give way to milder temperatures.
A low of -11.7C (10.9F) was recorded at Chillingham Barns in Northumberland in the early hours of Sunday morning, according to the Met Office.
In Scotland, a low of -12.6C (9.3F) was seen at Braemar in the Highlands, although it was a few degrees off the -15.4C seen there on Thursday.
The coldest spot in Wales was at Swyddffynnon in Dyfed, where -6.5C (20.3F) was seen, while in Northern Ireland the lowest temperature recorded was -2.6C in (27.3F) Katesbridge, Co Down.
Weather warnings are still in place for Sunday and Monday morning, but the next few days should see temperatures creep back into double figures in some parts of the country making it feel noticeably milder.
Simon Partridge, of the Met Office, said: “Things are picking up now as we start to see milder air push in from the South West through today.
“In South West England we could see plus 10C (50F), while more broadly across England it could be 6C (42.8F) or 7C (44.6F) degrees.
“Generally we are heading back to normal temperatures for this time of year this week – with a normal British winter situation, so it will be wetter and windier.”
Although it will feel milder, spring is still a long way off. Sky News weather forecaster Christopher England said: “The coming week will certainly see temperatures rise and it will get up to about 10 degrees in London.
“However, it will be unsettled with rain moving in. Although we will see milder temperatures, there’s nothing to say we won’t experience colder weather before the end of the month.”
A yellow warning of hill snow and ice for central and southern Scotland will kick in at midnight and run until 2pm on Monday.
Freezing conditions on Saturday saw motorists digging out cars trapped by heavy snowfall.
Drivers found themselves stranded on routes in Hampshire, including the M3.