The heavy rain that fell on Montreal flooded streets and a Hydro Quebec substation.
Rainfall warnings were in effect for the region as forecasters predicted 50 to 70 mm of rain would fall on the city and in surrounding areas.
67 mm fell at Trudeau airport, while 77.8 mm fell in downtown Montreal at the McTavish weather station.
The heaviest rainfall in Quebec was in St. Joseph du Lac, with more than 88 mm of rain falling overnight.
That rain led to dangerous conditions for anyone outside, and may be responsible for two pedestrians being hit in Montreal.
One woman was in critical condition after being struck by a car in St. Laurent.
Another individual was hit by a car where Cote de Liesse meets Highway 40.
Tens of thousands of people lost power overnight, and at its peak 116,000 customers were in the dark.
A Hydro Quebec power station in Hochelaga Maisonneuve flooded overnight, with the utility confirming that the majority of power failures in Montreal are due to the flooding of the Notre Dame substation.
By 7 a.m. Wednesday most power had been restored to all but 15,000 households in Montreal, but then something went wrong, and as of 8 a.m. more than 40,000 were without electricity.
Two hours later the number of people without power was even higher, at 47,000.
The rain ended overnight, and on Wednesday Montreal can expect a mix of sun and clouds with a high of 27.
