Winter storm, snowfall and blizzard warnings are in effect across a wide swath of southern Ontario and Quebec as a powerful low-pressure weather system rumbles north from the central United States.

The worst of it is expected tonight in Ontario, while Quebec and northwestern New Brunswick will be hit Wednesday morning, according to Environment Canada.

Snow was expected to become heavy at times overnight into Wednesday.

The Greater Toronto Area was expected to receive gusts of wind exceeding 60 km/h.

In the GTA, "snowfall amounts will generally be in the 15 to 25 centimetre range with lesser amounts to our south where icy precipitation precedes the snow," says CBC Toronto meteorologist Jay Scotland. "Snow wraps up by early tomorrow morning but blowing snow will likely remain an issue especially along exposed highways."

A freezing rain warning is in effect for Windsor, Ont., with a cold front expected to change the precipitation to snow in the early evening.

Early Wednesday, a winter storm warning ended for Sarnia and Lambton in Ontario.

New snowfall warnings are in effect for Baysville, Huntsville, Oxtongue Lake, Fort Irwin, northern Haliburton County, Deep River and eastern Algonquin Park areas.

Winter Storm generic woman walking snow

It's going to be a rough commute tonight in southern Ontario, and rough again Wednesday morning in southern Quebec and northwest New Brunswick. (Darren Calabrese/Canadian Press)

The winter storm system will hit southern Quebec by morning before continuing toward the Gaspé Peninsula.

A blizzard warning is in effect in many areas, including Montreal and Quebec City. Blowing snow is expected to cut visibility to near zero from Pontiac to Natashquan and Gaspé, Que.

Snowfall warnings are in effect in northwest New Brunswick, with 15 to 25 centimetres of accumulation expected.

Environment Canada said non-essential travel in these areas should be put off until after the system passes.