By Ismail Shakil and Rod Nickel

OTTAWA/WINNIPEG (Reuters) -Strong winds, freezing rain and heavy snowfall closed schools, cut power to homes and cancelled flights across Canada on Friday as a powerful winter storm swept across the country, prompting authorities to warn people to stay indoors ahead of worsening conditions.

The storm is connected to the same freezing weather system that has enveloped much of the United States ahead of the Christmas holiday weekend, thwarting travel plans and leaving more than a million homes and businesses without power.

The storm was expected to affect about two-thirds of all Canadians as it moves across Canada’s two most populous provinces, Ontario and Quebec, toward Atlantic Canada, said Environment Canada meteorologist Steve Flisfeder in Toronto.

“Every winter we expect storms (but) this one is significant,” he said. “We’re seeing differing weather types that are all leading to different impacts … affecting a very large population base in a short time span.”

Winter storms have increased in frequency and intensity over the past 70 years, according to the U.S. Global Change Research Program. This is in part due to climate change, according to the Environmental Defense Fund, because the planet evaporates more water into the atmosphere as it warms, leading to more overall precipitation.

Canada’s second-largest carrier WestJet Airlines proactively cancelled all flights at airports in Toronto, Ottawa and the province of Quebec, citing bad weather. The largest carrier, Air Canada, also warned of delays and cancellations.

Nearly 320 flights or about a third of all scheduled arrivals and departures on Friday were cancelled at Canada’s busiest airport, Toronto’s Pearson, with another 200 delayed, according flight tracking website FlightAware.

Alberta, Canada’s main cattle-producing province, was under extreme cold warnings from Environment Canada.

Some farmers positioned portable wind breaks and used treed areas to protect their herds from potentially deadly winds, said Karin Schmid, beef production and extension lead at the Alberta Beef Producers industry group.

Cold temperatures can kill cattle but such deaths are rare, and Schmid said she was not aware of any this week.

In Ontario, stormy weather reduced transport of cattle to feedlots and slaughter plants, but the holiday season is slow anyway, said Jack Chaffe, who runs a 2,000-head feedlot.

The power utility in Canada’s capital city Ottawa said it had restored electricity for nearly 100,000 customers and was working to fix outages for 9,000 more. In Quebec, nearly 270,000 were without electricity on Friday afternoon.

Ontario Provincial Police Sergeant Kerry Schmidt said police had received reports of up to 100 vehicles involved in multiple collisions that have closed off a major highway near London, Ontario.

“The wind and snow is blowing in and today is going to be a tough day for a lot of drivers,” Schmidt said in a video message posted on Twitter. “The best place is off the highway.”

In the Pacific province of British Columbia, the storm brought several inches of snow overnight before transitioning to freezing rain and ice pellets, forcing the closure of key bridges and roads.

Conditions there are expected to continue changing as temperatures rise and bring heavy rainfall throughout Saturday and into Sunday, said Terri Lang, an Environment Canada meteorologist who tracks western Canadian weather.

“It’s going to be kind of a sludgy, sloppy Christmas, it looks like,” Lang said.

(Reporting by Ismail Shakil in Ottawa and Rod Nickel in Winnipeg; Editing by Josie Kao)

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