Ferocious winter weather grounded flights and stranded nine Via Rail trains between Ontario and Quebec on Saturday as snow, freezing rain, high winds and rain hammered much of the country and plunged Christmas Eve and Day travel plans into chaos.

Power outages and impassable roads prompted three towns in Ontario's Niagara region to declare a state of emergency and beg residents to stay off the roads, while New Brunswick grappled with one of the largest power outages to befall the province in decades.

The only provinces or territories not affected by an Environment Canada weather warning or statement as of Saturday early evening were Nunavut and Nova Scotia.

In a tweet Saturday early evening, Via Rail said a CN train derailment forced the cancellation of all trains between Toronto and Ottawa and Toronto and Montreal scheduled for Christmas Day.

Vee Grunda was one of many passengers stranded without food or water aboard a Via Rail train in Cobourg, Ont. She said the train came to a halt around 11 p.m. on Friday and by noon Saturday, many were still on board and seeking answers about what to do next.

"We've had some panic attacks and then we have some people with diabetes. We have a two-month-old baby, we have a bunch of elderly people," Grunda said in a telephone interview. "They haven't turned the lights off so no one slept. Everything's just tense."

Some passengers jumped off the train and ventured into the snow, climbing through backyards in search of a main road, she said.

A replacement train eventually arrived to take Grunda and her fellow passengers on to their destination.

Via Rail said nine trains running between Quebec City and Windsor, Ont., were halted by weather-related power outages or downed trees. Seven more trains were cancelled entirely on Saturday morning, the rail company said in a statement.

Some passengers said on social media that they were stranded aboard trains for more than 18 hours without food or water.

The company said it tried to keep customers as comfortable as possible and get them to their final destinations, either by getting the frozen trains moving or by bringing new trains that could safely transport passengers.

But federal Transportation Minister Omar Alghabra issued an afternoon tweet describing the situation with the national rail carrier as "unacceptable."

"We are in contact with them to resolve all issues safely and efficiently," he wrote. "The unprecedented weather has caused delays in our transportation system and the safety of passengers and crew is our top priority."

In a statement, Mark Strahl, Conservative shadow minister for transportation, said bad weather is not an excuse for the government's inaction when cold weather and winter storms are the norm and not the exception.

He said a Conservative government would "fix Canada's transportation system and demand answers from millionaire CEOs for why their airlines have failed so many Canadians, especially after getting billions of dollars in COVID related aid and funding."

In southern Ontario, the communities of Port Colborne, Wainfleet and Fort Erie all declared a state of emergency, citing power outages and dangerous driving conditions.

"Going out could put you in jeopardy and peril as emergency first responders may not be able to respond to calls," said Wainfleet Township in a tweet.

"If you are at home without power, please do what you can to conserve heat, help friends, family and neighbours where it is safe to do so," said a warning on the City of Port Colborne's website.

The Niagara Regional Police Service also appealed to the public to stay home, writing in a news release that emergency crews may be unable to respond to calls because roads were impassable.

By about 5 p.m. Saturday, the massive storm to blame for all the chaos had affected six provinces and was moving over Ontario and Quebec, said Environment Canada meteorologist Victoria Nurse.

Parts of southern and northeastern Ontario would likely see snow squalls coming off the Great Lakes over night and into Christmas Day, she said.

"It's definitely a big deal," she said. "One of the greatest impacts has been the wind that led to so much blowing snow and reduced visibilities and collisions on the roads.

"So our biggest takeaway today and going into tomorrow is, travel very carefully. Try and avoid travel, but if you have to travel, travel very carefully."

Ontario Provincial Police reported the province's first traffic fatality since the storm began, and officers were investigating whether or not extreme weather conditions played a part.

Hydro One said just over 50,000 customers were without power in Ontario as of Saturday early evening.

In Quebec, Environment Canada warned of heavy snowfall and blowing snow in the southwestern regions of Matagami and Waskaganish, as well as storm surge along the coastal areas of the St. Lawrence River.

Hydro-Quebec reported more than 183,000 customers in the dark on Saturday evening. The situation prompted a tweet from Premier Francois Legault.

"I know it's not the Christmas that many hoped for," he wrote. "Hydro-Quebec teams are doing all they can to reconnect as many homes, as fast as possible."

"Please, check-in with your loved ones if they live alone. Be careful on the roads, as well, the conditions are not ideal. For those who want to warm up, places are ready to receive you in many cities and municipalities."

Flights were cancelled and delayed at major airports in Ontario and Quebec and police closed sections of provincial highways due to hazardous driving conditions.

A company statement said WestJet cancelled 60 of its 500 scheduled flights on Saturday. The airline has cancelled 1,307 flights since Dec. 18.

In Ontario, staff at a pet boarding service in the Oro-Medonte township near Barrie were fielding calls from owners sidelined by weather delays who couldn't get home to retrieve their furry family members.

"We have some owners who aren't going to make it back, but they're happy their pets are safe here for Christmas with us," said Tallis Kostuik, operations manager at Royal Pets Hotel and Enrichment.

Rain and high winds were also forecasted through Christmas Eve in the Maritimes, with the storm projected to move into Newfoundland and Labrador on Saturday night.

More than 25,000 customers on Canada's east coast were without power early Saturday evening, with the bulk of those -- over 18,000 -- in New Brunswick.

A statement from NB Power said over 71,000 customers were without power at the peak of the outage.

"This is one of the largest provincewide outage events of the last 25 years," said company spokesperson Marc Belliveau.

On the other side of the country, most of southern British Columbia was under a rainfall warning. Environment Canada called for accumulations between 25 and 50 millimetres in the Metro Vancouver area, with more expected near the North Shore Mountains.

Vancouver Island could see up to 125 mm, with parts of the island as well as Howe Sound, the North Shore Mountains, Metro Vancouver and the Fraser Valley all under flood watch on Saturday.

B.C.'s River Forecast Centre said more rain on Sunday through Tuesday may lead to ongoing high flows and persistent flood hazards into next week.

After about half of the flights out of Vancouver International Airport were cancelled Friday, president and CEO Tamara Vrooman said Saturday that the airport was fully operational and about 93 per cent of scheduled flights were departing.

"Some cancellations are coming through because of weather events in other parts of the country and other parts of the continent, but for the most part we're operating as normal here at YVR," she said.

This report by The Canadian Press was first published Dec. 24, 2022.

-- With files from Tyler Griffin in Toronto, Jacob Serebrin in Montreal, Lyndsay Armstrong in Halifax and Ashley Joannou in Vancouver.