Thousands of homes have been left without power as many parts of the country were hit by snow and sub-zero temperatures.
The temperature dropped to minus 17.3C at Braemar in Aberdeenshire on Monday into Tuesday, making it the coldest place in the UK for the second night in a row.
A Met Office yellow warning of snow and ice for northern Scotland has now been extended from midday on Thursday until midday on Friday.
In Shetland, thousands of homes were left without power on Monday evening following significant snowfall.
As of 11am on Tuesday, power had been restored power to more than 2,500 properties, with 3,800 homes still off supply in Voe, Whalsay, Brae, Tumblin, Yell and Unst, Scottish and Southern Electricity Networks (SSEN) said.
SSEN warned that it may take until the end of the week to restore power to all customers due to the extent of damage, significant travel restrictions and continued issues accessing fault locations.
Mark Macdonald, Head of Region at SSEN Distribution, said engineers have been out since first light working to reconnect people.
He said: “We’ve seen extensive damage to the overhead power lines connecting homes and businesses, including multiple points of damage caused by snow and ice accretion which was not forecast. Our local teams have described the conditions as the worst they’ve seen in over 20 years.
Mr Macdonald added: “I’d like to reassure our customers we’re doing everything we can to restore power as quickly as possible and would encourage anyone who may be in a vulnerable situation to contact us on the power cut helpline, 105.”
All schools in Shetland were closed on Tuesday due to the weather conditions, while several schools were closed in Aberdeenshire.
Police in Shetland urged people to take care if they have to venture out.
Inspector Sam Greshon said: “With adverse weather expected to continue today, consider travelling only if you have to.
“Leave extra time for essential journeys and take warm clothes, food and water in case of any delays.
“Take a mobile phone with you and check it is fully charged.”
Many parts of Scotland experienced sub zero temperatures overnight, with minus 14.9C recorded at Balmoral, minus 13.6C at Aviemore and minus 12.9C at both Dalwhinnie and Tulloch Bridge, the Met Office said.
Authorities warned of wintry conditions on the roads and urged people to drive with care.
Meanwhile, in Aberdeen, the icy conditions affected traffic lights.
Aberdeen City Council tweeted: “Due to the on-going below 0C temperatures, several traffic lights around the city are experiencing issues with mechanical buttons or other parts freezing, resulting in shortened sequences.
“Engineers are using de-icer on the units, however, the units may freeze again.”
Forecasters said that the wintry conditions will continue into the weekend though may improve next week.
Met Office spokeswoman Nicky Maxey said: “The cold weather will continue for the rest of the week and into the weekend.
“At the start of next week, there is potential for some milder wet and windy weather to move in.
“It does not mean we’ve seen the last of the cold weather as we are still in December and there is certainly a chance of another spell of cold weather.”
The Met Office yellow warning says that wintry showers will affect many areas of northern Scotland and parts of north-east England, though will tend to become fewer in number from later on Thursday.
A few centimetres of snow are likely to accumulate at low levels with the potential for as much as 15-20 cm over higher ground.