Power crews have yet to restore service to more than 65,000 Hydro One customers who were left in the dark following Wednesday's severe thunderstorms.
Hydro One said they have restored power in many areas following Wednesday's storms, which knocked out power to roughly150,000 customers.
"Hydro One crews continue to make progress repairing damage from the thunderstorms. About 65,000 customers remain without power," the utility said on Twitter at around 9:40 p.m. ET on Thursday.
High winds and falling trees broke more than 300 hydro poles, and damaged and downed power lines across the province, said Hydro One spokeswoman Nancy Shaddick.
"We anticipate that the restoration efforts will take several days due to the volume of damage in many different locations," Shaddick said Thursday afternoon.
Bancroft, Kingston, Peterborough and Tweed were among the hardest hit communities, Shaddick said.
Shaddick said roughly 1,300 workers were working on power restoration efforts Thursday.
No confirmed tornadoes
There were several reports of possible tornadoes in Ontario, but Environment Canada has yet to confirm any of the reports.
"The sheer volume of reports of storms for the last few days will take us a few days to work through," Environment Canada meteorologist Geoff Coulson said Thursday.
Among the storms reported Wednesday was a possible tornado near Minden Hills, about 200 kilometres northeast of Toronto. A possible tornado was also reported in nearby Coboconk, Ont.
Coulson said Thursday that damage survey teams believe the incidents in Minden Hills and Coboconk were not tornadoes.
"In both cases it was determined to be a downburst, or a damaging wind event," he said Thursday.
Downbursts are localized gusts of powerful winds that come out of the base of a thunderstorm, Coulson said. He said the downbursts can be extremely dangerous and urged people to be cautious and seek shelter during extremely windy weather.
Local reports also said a pilot was killed when a gust of wind flipped over a float plane on Balsam Lake, about 150 km northeast of Toronto.
In Vaughan, northwest of Toronto, lightning was responsible for 15 building fires — six of them with significant damage to roof and attic areas.
Ottawa was hit with heavy rain, strong winds and hail reportedly the size of marbles.
Police said there were downed hydro lines, trees that came down on cars and homes, and traffic lights out at several intersections.
Two fires may have been started by lightning, fire officials said, but there were no injuries or major damage.
In Orléans, several roads were flooded and manhole covers came off the road due to the force of the water coming up through the drainage system.
East of the city, in the rural community of Sarsfield, high winds tore the steeple off the St-Hugues Catholic Church, which was built in the late 19th century.
In Gatineau, Que., the storm blew the roof off a three-storey apartment.
The same system that pushed through eastern Ontario later hit Montreal.
The severe weather came as humidex ratings for southern Ontario reached what felt like the low 40s.
Wednesday storm timeline:
1:30-2 p.m. Muskoka, Lake of Bays: power lines down
1:30-2 p.m. Muskoka, Acton Island: numerous trees down
1:30-2 p.m. Bracebridge, power outage, trees down
2-3 p.m. Minden, southern Haliburton, Kawarthas: trees down, damaged
5-5.30 p.m. Ottawa: 1.2 cm diameter hail
5-6 p.m. Orleans: 94 mm rain in half an hour
6.50 p.m. Bathurst-Hwy 7: golf-ball-sized hail
7 p.m. Yonge and Steeles: nickel-size (2.1 cm) hail
7.10 p.m. Bowmanville: 3.5 cm diameter hail
Source: Environment Canada