Hydro crews in Quebec and Ontario are gradually restoring power, but some people might be left in the dark until Tuesday.
The storm, which brought winds up to 100 kilometres an hour in some places, uprooted trees, brought down power lines, and even overturned some cars.
Quebec was particularly hard hit. At the height of the storm, about 560,000 Hydro Québec customers had lost electricity.
Power was restored to over 90 per cent of customers in Montreal but other areas north of the city could take longer, said a spokesman for Hydro Québec.
Louis-Olivier Batty said workers still need to clear away trees and branches from some power lines.
Trouble spots in Quebec include Laval, the Laurentians, Lanaudière as well as the Outaouais region near Ottawa.
In Ontario, about 36,000 Hydro One customers were without power as of Sunday afternoon.
A municipal worker in a Montreal suburb was killed by a falling tree during the storm, while at least 10 others were injured across Quebec.