Regional authorities say the storm damage is the "most significant" they have ever had to deal with.
Around 30,000 people in the north of England and Scotland are still without electricity after Storm Arwen.
Strong winds have brought snow, ice, and severe disruption to the United Kingdom's infrastructure this week, while three people have been killed.
Arwen -- one of the most powerful storms in decades -- initially knocked out power to hundreds of thousands of people with winds of up to 160 km/h.
UK Business Secretary Kwasi Kwarteng told Parliament that almost 1 million people, or about 95% of those affected, have had their power restored.
But an estimated 30,000 were still without power on Wednesday, five days after the storm first hit.
Kwarteng said the country needed to be prepared for more extreme weather due to climate change.
Chris Burchell, managing director of Scottish and Southern Electricity Networks, apologised to customers and said the damage caused by Arwen was the "most significant event we have ever had to deal with in the area in a generation.”
The Energy Networks Association said that some households would not get their electricity back before the end of the week.
Shelters have been set up and hot meals provided to affected residents, with energy companies working in partnership with the emergency services, local authorities, and the British Red Cross.