Military helicopters were brought in to help rescue drivers stranded by blowing snow in southwestern Ontario, while wind and rain pound parts of Atlantic Canada.

In southwestern Ontario, the Ontario Provincial Police said 237 motorists stranded by snow along a closed Highway 402, which runs from Sarnia to London, had been rescued as of 3 p.m.

Ontario Community Safety Minister Jim Bradley believed all the stranded motorists had been rescued, but police were checking each vehicle. It wasn't clear how many drivers had been rescued by other citizens.

A pair of military helicopters were being used to airlift some people from the road, while snowmobiles and four-wheel drive vehicles collected others.

Speaking at a warming centre in Strathroy, Ont., Dana Peart said driving conditions in the blowing snow Monday night were scary.

"You couldn't see out your windshield at all," she said. "Your lights were completely darkened from the snow sticking to the car. It was terrible.

"We weren't sure at any time if we were on the road when we were trying to drive to find a hotel to get out of the snow for the night."

Another motorist caught by snow was Dan Michaelis.

"Well, last night, I ran out of gas, and couldn't feel my feet or my fingertips," he told CBC News, from a Tim Hortons outlet in Lambton County.

Sarnia police check on stranded motorists on London Line, east of Sarnia, Ont., on Tuesday. (Glenn Ogilvie/Canadian Press)"That is when I started to panic a little bit because I couldn't get into any other trucks, and it was miserably cold outside. So, thanks to my family, they had also called the OPP and I got a cold ride on a snowmobile."

Truck driver Todd MacDougall, who was stranded in his vehicle about 20 to 30 kilometres outside Sarnia with a load of cardboard, was riding out the storm in the cab of his truck.

"The fuel, I've got just under half a tank, so it all depends how long I'm here for, I guess, but I've got enough fuel if we get going this afternoon or tomorrow morning.

"Food, I've got enough for the next day or so, and I've got lots of water. I try to pack extra, especially in the wintertime because you never know when you're going to get something like this."

Sarnia police said officers and road crews have placed themselves in danger to assist stranded motorists, some of whom had driven through police barricades at road closures.

Snow squalls were expected to drop 15 to 20 centimetres of snow to the lee of Lake Huron and southern Georgian Bay on Tuesday, Environment Canada said.

Blue Mountain ski resort near Collingwood, Ont., was closed Tuesday citing high winds, blowing snow and road closings.

Snow led General Motors to send employees home and cancel shifts at its Oshawa and Ingersoll, Ont., production plants. The weather created problems shipping parts to supply the plants.

Roof collapses in N.S.

The Maritimes endured heavy rains and high winds, including in Windsor, N.S., where the wind collapsed the walls and roof in an unoccupied rear section of a assisted-living centre for senior citizens late Monday. None of the 13 residents was hurt and they were evacuated from the building after midnight local time.

The rear section of Kingsway Gardens in Nova Scotia collapsed overnight, forcing residents to evacuate. (Phonse Jessom/CBC)

In New Brunswick, heavy rains that topped 170 millimetres and in some cases led the province's Emergency Measures Organization to issue a series of flood warnings. A shopping mall in St. Stephen, at the border with Maine, was hit by flooding with most tenants affected.

Some roads in the Fredericton area were washed out.

Power outages persisted across many parts of Nova Scotia and New Brunswick, leaving thousands of consumers in the dark.

Rainfall warnings were posted Tuesday for eastern Nova Scotia, including Cape Breton. Up to 130 millimetres of rain were expected in some areas.

Portions of Newfoundland were under wind warnings, with gusts of up to 150 kilometres an hour forecast for the Wreckhouse region in the southwestern corner of the island.

Environment Canada also issued snowfall warnings for areas of Alberta to the north and east of Edmonton. Snowfall warnings were in place for portions of southwestern Manitoba, while freezing rain was forecast for southeastern Saskatchewan.

With files from The Canadian Press