More than 2,500 homes remain without electricity after flash floods swept across North Yorkshire.
Residents in North and East Yorkshire found themselves without power on Sunday after a night of heavy storms.
Villages were cut off, roads washed away and nine people were rescued by RAF helicopter crews when a deluge of flood water swept through the area.
A spokesman for electricity company YEDL said it was hoped to have all power restored by Monday evening.
He added that floodwater in Helmsley, about 20 miles north of York, and damaged roads in nearby Hawnby was making access to the area difficult and hampering work to restore supplies.
Residents in South Shields, Sunderland and East Yorkshire were also affected by the power cuts and flooding.
An electricity sub station in Beverley, East Yorkshire was one of the many places to be struck by lightning during the storms.
Tributes have been paid to those involved in the rescue operation by Elliot Morley, minister for flood defence.
"It's clearly been traumatic for those affected," said Mr Morley.
"This was an extreme event, with one month's rain falling within two or three hours. It is a reminder that flooding can happen at any time and in unexpected places."
The flooding followed a weekend of high temperatures across the UK which left four people dead from drowning.
In North Yorkshire, drivers were forced to abandon their cars and climb trees to escape rising waters after the River Rye burst its banks with water rising four or five feet within minutes.
The flood waters forced many residents to leave their homes for the night.
The downpour over the North York Moors cut off a number of villages, with Thirsk, Carlton and Sutton-under-Whitestonecliffe among those affected.
Early on Monday, North Yorkshire Police said the A170 and B1257 roads remained closed. The bridge leading into Helmsley was described as looking perilous.
A spokesman said the roads would remain closed for "quite some time", although the flood waters had reached their peak just after 0130 BST and were "going down satisfactorily".
The main flooded areas are on the edge of the North York Moors
The storms first hit the area at about 1700 BST on Sunday.
RAF crews from North Yorkshire and Wales scoured the area and rescued people from cars, trees and the roofs of isolated homes.
One elderly woman who had suffered a heart attack was winched to safety in Hawnby, which was reported to have been cut off.
Carol Swift, a fish and chip shop owner in Helmsley, said the town, which has a population of about 2,500, had been devastated by the flood.
The waters threatened to engulf the bridge over the River Rye - the only way into the picturesque market town.
"The water is right up to the top of the bridge, I've never seen anything like it," she said.
"But everyone will rally round in Helmsley, we shall recover very quickly from this."
Craig McGarvei from the Environment Agency said climate change may have played its part in the sudden flooding which in Helmsley saw three inches (7.6cm) of rain fall in an hour.
"A lot places that have been flooded are not normally flooded," he explained.
Thunderstorms and torrential rain also caused localised flooding in Newcastle.
The Tyne and Wear fire service was inundated with so many flood-related calls that other brigades, including one based in Scotland, had to help.
In Newton Aycliffe hailstones as big as marbles reportedly damaged cars.
And a deluge of water swamped a public house and a row of shops in the main shopping street in Chester-le-Street.
The weekend's heatwave led to four drowning incidents as people tried to cool off in the sea, in lakes and in rivers.
Two men drowned in Buckinghamshire and Hertfordshire while the body of a 23-year-old man was pulled from the sea near Babbacombe in Devon.
A boy of 16 died in hospital after being pulled from the River Thames at Sunbury in Surrey.