The storm, which brought winds up to 100 kilometres per 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 Quebec customers had lost electricity.
That number had been cut down to 80,000 by late afternoon on Sunday.
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 Quebec.
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, Lanaudiere 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 ten others were injured across Quebec.