About 150,000 customers were without power in Ontario Tuesday morning, 14,000 were in the dark in Nova Scotia and Hydro-Québec said about 50,000 customers were affected.
Power outages in Toronto resulted in the closure of more than a dozen schools for the day. Downed tree limbs, poles and hydro wires caused problems for the public transit system. About a quarter of the flights at Toronto's Pearson International Airport were cancelled.
Power was restored to more than 80,000 Ontario homes by early Tuesday afternoon, provincial Energy Minister Chris Bentley said, adding that the worst is over.
"We expect that given the progress that crews have made already that the numbers without power will come steadily downwards. But of course we are at the mercy of the weather," he said.
The strongest wind gust reported in Toronto was 91 km/h, recorded at the downtown island airport, according to the Canadian Hurricane Centre.
The most heavily affected areas were Toronto, Waterloo, Peterborough, Owen Sound and Sarnia
The strongest winds in Ontario (106 km/h) were recorded on Western Island in Georgian Bay, and in Quebec, Laval and Orléans experienced winds close to 90 km/h.
The most precipitation from Sandy came in the Charlevoix region of Quebec, where 55 mm of rain fell.
Sandy brought mixed precipitation to northern Ontario, with snow, ice pellets and freezing rain around Timmins and Cochrane. Wind gusts of up to 60 km/h are expected.
The precipitation could turn into snow over parts of Ontario and western Quebec, said Environment Canada.
A wind warning also remains in place for the Quebec City region, the Canadian Hurricane Centre said.
Higher than normal water levels and pounding surf were expected along the Atlantic coast of Nova Scotia and along the St. Lawrence River. Forecasters were warning that some coastal flooding could occur in the Quebec City region.
"We're still expecting a rain event for the Maritimes," said CBC weather specialist Craig Larkins. "Parts of Nova Scotia and New Brunswick could see 50 to 70 millimetres of rain."
The rain could persist into Wednesday.
Environment Canada's warning preparedness meteorologist Geoff Coulson said that winds from the storm were slowing, and most wind warnings have been cancelled, but the grey skies won't clear just yet.
He told The Canadian Press clouds will linger for the next few days, along with on-and-off showers, because of the slow-moving nature of the storm.
Southern Ontario bore the brunt of the storm after it moved into the region Monday evening, with powerful winds described as more of a concern than the rain.
Sarnia Mayor Mike Bradley told CBC News that waves on the community's shores reached six to nine metres overnight, the highest in recent memory.
"This is a storm reminding some people of Hurricane Hazel [in 1954], thank goodness not in the loss of life, but in the duration and anger of the storm," he told CBC News.
"No one has seen the St. Clair River look like this for at least a generation."
Woman killed by storm-blown sign in Toronto
Powerful gusts from the storm claimed a life Monday night in Toronto. Police said a woman was killed by a falling sign as winds of 65 km/h whipped through the city.
The woman, in her 50s, was hit in the head by a sign panel measuring about two metres wide while walking in a commercial parking lot near Keele Street and St. Clair Avenue. The panel was ripped off by a strong gust of wind, police said. The woman was pronounced dead at the scene.
Public Safety Minister Vic Toews had promised the military and the Canadian Coast Guard would be on standby to help deal with any havoc wreaked by Sandy.
Sandy made landfall in the U.S. Monday night, just after forecasters changes its status from hurricane to a post-tropical cyclone, but the distinction was purely technical, based on its shape and internal temperature.
"Typically, hurricanes, when they make landfall and become post-tropical [cyclones], they lose about 50 per cent of their energy in the first 24 hours. So we're going to see the remnants of Sandy really diminish in intensity through day," Environment Canada meteorologist Etienne Gregoire told CBC News.
Projected path for post-tropical storm Sandy
With files from The Canadian Press