Hurricane Irene was downgraded to a post-tropical storm late Sunday but it was still strong enough to knock out power to 180,000 homes in Quebec and cause dangerous storm surges in coastal areas.

Most of the power outages are in the Montreal area, as the outer fringes of the storm brought heavy rain and wind gusts of up to 90 kilometres an hour.

Montreal police reported fallen trees and some damage to houses and apartment buildings.

According to the U.S. National Hurricane Center, the centre of the remnants of Tropical Storm Irene was just nearing the U.S.-Canadian border at about 11 p.m. Sunday. 

Rainfall warnings of up to 100 millimetres have been issued for parts of Quebec and northwestern New Brunswick.

The Canadian Hurricane Centre has warned of potential flooding in Yarmouth, N.S. and along the Bay of Fundy. Wind gusts of up to 110 km/h, could be felt in the area, forecasters predicted.

Once a hurricane, Tropical Storm Irene is making its gradual journey up the U.S. East Coast and is expected to cross from northern Maine into northwestern New Brunswick sometime Sunday or early overnight.

Fredericton Mayor Brad Woodside said the biggest risk to his city and the surrounding area is from flooding as the Maritimes has already had above-average rainfall this summer.

"Our biggest asset could be our biggest liability and that's the beautiful Saint John River," he told CTV News Channel Sunday afternoon.

But he said emergency measures are in place and the city is as prepared as it can be for Irene.

As flooding is a yearly threat in the spring to the region, Woodside said New Brunswickers are perhaps a bit more prepared than many along the East Coast.

"People have become used to it and they know what to do," Woodside said.

New Brunswick Public Safety Minister Robert Trevors said people shouldn't take the storm lightly, even if it didn't have the impact in New York that was feared.

"We want New Brunswickers to stay prepared," he said. "We still have a time period yet before we're able to relax."

Meteorologist Chris Fogarty with the Canadian Hurricane Centre told The Canadian Press on Sunday that the heaviest rainfall is expected in Quebec's eastern townships, with the potential for flooding.

He said the strongest winds and coastal storm surge is expected for western Nova Scotia and southwestern New Brunswick.

Fogarty notes that although Irene is an intense storm, its strength will fluctuate as it moves up toward Canada.

"When they move up this far north, they change into what we call ‘post-tropical storms,'" he said. "The storm changes into a path that's very similar to a wintertime storm with high winds and heavy snow."

Fogarty said that Yarmouth, N.S. could see a storm surge causing potential flooding around midnight, while high tines on Monday in the Bay of Fundy could threaten coastal areas in the Chignecto and Minas basins.

Though Irene weakened to a tropical storm on Sunday morning, officials are still issued travel warnings ahead of its Canadian arrival.

Air Canada said flights involving airports in Atlantic Canada might also be affected and travellers were encouraged to check the status of their flights online before heading to the airport.

Irene has already played havoc with air traffic. Dozens of flights were cancelled to the northeastern United States on Saturday by airports in Toronto, Ottawa, Montreal and Halifax.

Fogarty predicts that when Irene's storm centre passes into Canada, considerable amounts of rain will drench the country's eastern seaboard.

"Storm surges will also be a bit of an issue, especially with wave action on top of that," he said. Fogarty added that parts of New Brunswick and Nova Scotia with high tides may be problem areas.

Strong gusts of wind are also an issue, said Fogarty in a phone interview from Dartmouth, N.S.

"We're expecting, nothing too severe, (winds) gusting to 90 or 100 kilometres per hour which could cause power outages or tree branches to break," he said.

Forecaster Jeremy March, who is also with the Canadian Hurricane Centre, predicts that Quebec's Eastern Townships and the western Gaspe area will likely get drenched with up to 150 millimetres of rain when Irene arrives.

Up to 50 to 80 millimetres could fall on western New Brunswick, he told The Canadian Press.

Irene's strongest winds will be felt in Nova Scotia where March predicts gusts of up to 100 kilometres an hour will be felt late Sunday and early Monday.

Fogarty said the storm front is so wide rainfall could affect areas around Montreal and as far west as Ottawa.

With files from The Canadian Press