Toronto Hydro says some of its customers might not have power until sometime on Thursday because of the "complex and time-consuming repairs" needed after the large-scale outage that, at one point, left tens of thousands in the dark. 

The utility company said late Wednesday its crews will be working through the night in the hardest-hit parts of the city, where about 3,100 of its customers are still without power. 

That's down from 87,000 customers at the peak of the problem. The blackout was partially blamed on the harsh weather that hit the city on Tuesday. 

"There is no doubt that progress is being made," said Toronto Hydro CEO Anthony Haines earlier in the day, noting that hydro crews will continue to work around the clock until all customers have power restored.

Toronto Etobicoke power outage

A building near Dixon Road and Islington Avenue lost power amid Wednesday night's storm. Etobicoke is one of the areas hit hardest by the power outages. (Tony Smyth/CBC)

Haines said the storm that struck Toronto on Tuesday created ice conditions on hydro poles covered in salt that has built up over the winter.

The combination of water and salt conducts electricity well. Haines said electricity was flowing through wires to poles that would catch on fire.

"We last night had just over 50 fires burn down poles in the course of roughly three hours," he said.

Haines said that pole fires are something the utility would deal with once every couple of weeks in a normal winter.

"So while the situation is not abnormal for the electric sector, you will no doubt have seen that this condition existed all over the GTA last night. In fact, the volume of it, really did make it quite unusual," he said.

The same conditions caused problems at a handful of power stations that supply electricity to the Toronto hydro system.

Temperature set to plunge

The weather has since improved, giving crews better conditions to make repairs.

While Environment Canada forecasts the temperature will plunge to –18 C overnight, Toronto Hydro spokesman Brian Buchan said the cold snap should have "no appreciable effect" on the repair process. 

Mayor John Tory spoke to reporters Wednesday, during an update on the power outages and issues with frozen pipes and water service to thousands of Torontonians.

Toronto Hydro CEO Anthony Haines

Anthony Haines, president and CEO of Toronto Hydro, spoke to reporters on Wednesday about his organization's efforts to restore power to thousands of its customers. (CBC)

Tory acknowledged that this winter has been difficult, but he remained optimistic the city can tackle its infrastructure problems.

"This extreme cold has been very hard on the people of Toronto and hard on the city in terms of different aspects of its infrastructure," he said. "It's been kind of a continuous arm-wrestle with Mother Nature, where we're going to win, but it's just taking us a little bit of time to do that."

Toronto Hydro's online outage map continues to track the remaining outages.

Other areas around Toronto were also dealing with outages on Wednesday.

PowerStream tweeted that some 4,000 homes were without power in the areas it serves, including Richmond Hill, Markham and Vaughan.

Enersource's online power outage map only shows one area affected by outages in Mississauga.