Temperatures fell to minus 17.1C overnight in the Scottish Highlands, setting a new 10-year low.
And the cold snap is set to continue, with the Met Office warning that temperatures could drop even lower overnight on Wednesday.
The temperature in Altnaharra overnight on Tuesday was the coldest since January 2010 when the temperature dipped to minus 22.3C.
>The same region of Scotland saw lows of minus 16.7C overnight on Monday.
The Met Office said that Storm Darcy, which caused much disruption last week, has now “definitely” moved on.
The NHS said that despite tough conditions many vaccination centres had remained open, and any missed appointments would be rescheduled.
Yellow warnings for ice and snow were still present down the length of the UK on Wednesday, though some will remain in place in parts of northern England and Scotland on Thursday and Friday.
The Met said that a “rash of snow showers” was expected through until Wednesday morning but that “erratic” weather fronts would dominate the rest of week.
Daytime temperatures are forecast to hover in the single figures across the whole of the UK on Wednesday and Thursday.
Several councils in England, including Rugby Borough Council and Southwark Council, in London, were forced to briefly suspend waste collection services due to the weather conditions.
Thurrock Council, in Essex, said that more than 100 workers, mostly from street cleaning and waste collection teams, were diverted from regular duties to help clear snow from footpaths and routes to medical centres.
The low temperatures will cause pavements and roads to remain icy for the rest of the week, said Grahame Madge, a spokesman for the Met Office.
It comes after Age UK urged people to make extra checks on elderly friends and relatives and warned against travelling through treacherous conditions to receive vaccinations.
Director of Age UK Caroline Abrahams reminded those due to attend that vaccination appointments were “not a one-off” opportunity.
Cold temperatures increase blood pressure, which can trigger heart attacks and strokes in elderly people, and breathing in chilly air can increase the impact of illnesses like flu and pneumonia.
Vaccination centres in Ipswich and Bury St Edmunds in Suffolk and Clacton-on-Sea and Colchester in Essex were closed on Tuesday due to the severe weather.
An NHS spokesperson said: “The vast majority of vaccination centres have remained open despite Storm Darcy but where sites have had to close for safety reasons the vaccine intended for use there is redirected to an open site to ensure all available vaccine is used as quickly as possible.
“Any appointments which could not take place due to centre closures are being rescheduled.”