High winds and snow stranded hundreds of motorists on a stretch of highway in Ontario late Monday night, as fierce winds battered Atlantic Canada.

Ontario Provincial Police estimated that more than 360 vehicles were stuck on Highway 402 near Sarnia, as the surrounding County of Lambton declared a state of emergency.

"Motorists are encouraged to remain in their vehicle and consider pooling vehicle resources until rescuers are able to reach their location," OPP said in a press release. "Motorists are also encouraged to ensure their vehicle exhaust is clear of snow to ensure clean air supply to the vehicle interior.

Meanwhile, winds ripped through Atlantic Canada with gusts measured at 100 kilometers an hour -- 140 km/h in western Cape Breton. They also churned up waves in the ocean, delaying ferries in Nova Scotia and Newfoundland.

The same weather system drenched parts of New Brunswick with heavy rain. Up to 130 millimetres could fall by Tuesday morning, but by Monday night some streets in Fredericton had already been flooded.

The storm is centred on the same cold front that buried parts of the U.S. upper Midwest over the weekend, dumping as much as 50 centimetres of snow on Minnesota and collapsing the roof of the Metrodome in Minneapolis.

Although snowfall associated with the system has eased, the agency said strong northerly winds behind the storm mean squalls and blowing snow.

In Quebec, residents in the south were expecting to see freezing rain, with snow falling in the north.

Temperatures plummeted in Ontario overnight, prompting officials to issue flash-freezing warnings for south-central parts of the province.

"A flash freeze occurs when moisture and some accumulating snow on roads creates icy conditions as the mercury falls quickly below freezing," the weather service explained on its website.

A sharp wind chill made the afternoon temperature in Toronto feel like it was -20 degrees Celsius.

Ontario provincial police were urging people living an hour north of the city to stay off of the roads except in the case of an emergency due to icy conditions and limited visibility.

Earlier in the day, a large swath of southern Ontario was under a weather warning including London, which last week had been punished with more than a metre of snowfall in some areas.

Environment Canada said damaging winds gusting up to 90 km/hr were being felt near the shores of Lake Huron.

Freezing winds coming off the lake were bringing 15 to 20 cm of snow to Georgian Bay and reducing visibility to zero in some areas.

"Dangerous winter driving conditions are likely, due to low to nil visibility in heavy snow, blowing snow, and from accumulating snow. Travellers should adjust plans accordingly," Environment Canada said.

The powerful storm has also cancelled more than 1,600 flights, including several from Canadian airports to New York, Chicago and Boston.

At least six deaths were reported in the U.S. during the weekend as the winter storm cut a freezing swath across the Midwest.

Minnesota and Wisconsin received nearly 60 centimetres of snowfall over the weekend and the National Weather Service was calling for more snow and freezing temperatures in Michigan, northern Indiana, Pennsylvania and New York.

"With the snow, pretty much the worst of it's over, but we're going to get cold temperatures through Tuesday," Jim Taggart, National Weather Service meteorologist in Chanhassen, Minn, told The Associated Press.

With files from The Canadian Press and The Associated Press