The northeastern U.S. will feel the brunt of Hurricane Sandy as it churns north this weekend, but huge chunks of Canada are expected to take a hit as well.
"As many as 23 million Canadians stand to be affected by this storm," said meteorologist Mark Robinson at the The Weather Network. "That's 70% of the country.
Tropical cyclone Sandy revved back up to hurricane strength on Saturday as it churned toward the U.S. northeast coast, where it threatens to become one of the worst storms in decades.
The late-season storm has been dubbed "Frankenstorm" by some weather watchers because it will combine elements of a tropical cyclone and a winter storm and is expected to reach the U.S. coast close to Halloween.
On Saturday , Environment Canada said southern and eastern Ontario and western Quebec will be hit by the heaviest rainfall, possibly reaching between 50 to 100 mm by Tuesday.
Flood warnings were issued across southern Ontario, including for Toronto, on Saturday.
The Toronto and Region Conservation Authority is advising drivers to use caution and avoid driving through low-lying roadways and underpasses. Parents are also being urged to keep children away from swollen and raging rivers and streams.
"Steady rain over a couple of days ... fills up the moisture-holding capacity of the soil," said the TRCA's Ryan Ness.
Heavy rain could also affect parts of the Maritimes and possibly turn into snow over parts of south-central Ontario and western Quebec as temperatures near the freezing mark north and west of the storm.
"We could see thousands of trees down and millions without power in Ontario and Quebec by early next week," said Weather Network meteorologist Chris Scott.
Normally, large hurricanes like Sandy hit Canada's east coast the hardest, clipping the Maritimes and Newfoundland. But meteorologists say a high-pressure system over the Maritimes will likely block Sandy's advance and push it into the mid-Atlantic states on late Monday or Tuesday.
"Everyone in the Maritimes, certainly everyone is southern Quebec and eastern and southern Ontario should be monitoring this storm," Canadian Hurricane Centre spokesman Bob Robichaud told the Weather Network.
"I know it's a big area but it speaks to the size of this storm. ... It's getting a lot of attention and deservedly so."
A ship carrying nearly 5,000 passengers to the Maritimes will divert at the Port of Saguenay, Que., Sunday because of the impending hurricane. It's the largest ship ever hosted in the region.
"We did not expect it. We had closed the books for the season two days ago, "said Mayor Jean Tremblay in French.
South of the border, the storm threatens torrential rains, high winds, major flooding and power outages a week before U.S. presidential and congressional elections.
Republican presidential candidate Mitt Romney cancelled a rally scheduled for Sunday evening in Virginia Beach, Virginia, while Barack Obama's re-election campaign announced that Vice-President Joe Biden had also cancelled a Saturday trip to that city.
New Jersey Govenor Chris Christie ordered mandatory evacuations between Sandy Hook south and Cape May.
"One of the reasons Sandy is making news is because it could be hitting some of the most heavily populated areas in Canada and the U.S.," said Robinson.
"Sandy has the potential to bring significant storm surge into major cities, like Manhattan. In a worst case scenario, New York City could be inundated with up to three metres of storm surge water. That would put some of the most valuable real estate on the planet under water."
On its current projected track, Sandy could make U.S. landfall on Monday night or Tuesday somewhere between North Carolina and southern New England, forecasters said.
The storm has the potential to cause widespread power outages and to unleash flooding and even dump snow as far inland as Ohio. It also threatens to disrupt air travel along the U.S. east coast.
Sandy has already claimed at least 59 lives as it made its way through the Caribbean islands, including 44 people in southern Haiti, mostly from flash flooding and mudslides, according to authorities.
Another 11 people died in Cuba, largely due to from collapsed buildings, officials said.
-- with files from Terry Davidson, Danny Gauthier and Reuters