A municipal employee in the community of Boucherville died when a branch fell in a local park.
Two other people were injured.
Eight children were injured in Prévost when a tent set up at a day camp to protect children from rain had collapsed on its occupants.
The violent storms swept through Ontario and southwest Quebec.
Fallen trees and snapped branches downed countless powerlines, leaving 425,324 customers without power on Friday night.
Hydro Quebec crews were to work through the night to restore power.