Atlantic Canada is bracing Monday for heavy snowfalls from the same massive weather system that has hammered Ontario and Quebec.

At least 10 centimetres of snow fell in Vancouver on Sunday.
(CBC)

The official start to winter may be still three weeks away, but wintry weather is already blasting much of Canada.

"It's going to be a very messy day across a good part of the country," the CBC's Colleen Jones said early Monday.

Many Canadians were still digging themselves out after three weather systems brought snow to much of the country over the weekend, with systems moving up along the Atlantic and Pacific shorelines as well as through Central Canada.

Environment Canada's senior climatologist, David Phillips, remarked Sunday that if Monday were Dec. 25, "we'd have a white Christmas from coast to coast to coast." By Monday's end, Phillips said, snow could be everywhere.

Rain brings new woes to B.C.

Many residents in southern B.C. didn't get the chance to shovel away the five to 50 centimetres of snow that fell over the weekend before rain washed it away.

A pedestrian walks on a snow covered street on Monday in Quebec City. Between 15 to 30 centimetres of snow are expected in the region.
(Jacques Boissinot/Canadian Press)

Flooding is now a concern as river levels rise. A flood watch was issued for Greater Vancouver, south and central Vancouver Island, Howe Sound and the Lower Fraser Valley, with 40 to 260 millimetres of rain expected by the end of Monday.

But other parts of the province were still feeling the chill of winter, with freezing rain and snowfall forecast for parts of the southern Interior and southeastern B.C.

At the other end of the country, thousands of residents in eastern Newfoundland awoke to darkness over the weekend after heavy snow and strong winds brought down power lines. Crews inspecting the electrical lines said it was some of the worst damage they've seen in a decade. More than 45 centimetres of snow fell in Gander and more than 20 centimetres in St. John's.

That same storm struck Nova Scotia and Prince Edward Island, dumping more than 20 centimetres of snow.

The latest storm that is now tracking through Ontario and Quebec is expected to move into Atlantic Canada by Tuesday morning. Up to 50 centimetres are forecast for New Brunswick and up to 40 centimetres for Nova Scotia. In anticipation of the heavy snowfalls, school officials in southwestern Nova Scotia closed some schools earlier than usual.

Storm slams Ontario, Quebec

Large sections of Ontario and Quebec were already under weather warnings Monday as a storm system moved in from Colorado.

An OPP police officer walks toward the cab of a transport that slid off Highway 401 in Brockville, Ont., on Monday.
(Darcy Cheek/Brockville Recorder and Times/Canadian Press)

Up to 20 centimetres of fresh snow promised to bury much of eastern Ontario and western Quebec. Ten more centimetres were also in the forecast for Montreal, which got about 15 centimetres over the weekend.

A number of flights at Montreal's Pierre Elliott Trudeau International Airport were cancelled or delayed, while the Ottawa International Airport faced some delays.

In the Prairies, meanwhile, many parts were shivering through a temperature of -25 C with wind chill.

Environment Canada warned of a potentially severe winter weather system moving in from Alberta that could bring 10 to 20 centimetres of snow to southwestern Manitoba and southeastern Saskatchewan.

With files from the Canadian Press