Severe thunderstorms

Last updated April 19, 2024

What damages can a severe thunderstorm cause? What services does the city offer to prevent flooding in buildings during a heavy rainfall? Learn more about the risks of thunderstorms in Montréal.

Safety risks

Severe thunderstorms can be accompanied by lightning, strong winds, a tornado, hail, and a heavy downpour. The force of these storms can cause flooding, power outages, fires, electrocution, landslides and significant damage to infrastructures, such as buildings and streets.


Heavy rainfall during a severe thunderstorm can cause a significant accumulation of water in the streets. Residents can request an immediate response from the city when the situation is reported to 311.

A risk of flooding also exists for homes not protected by properly installed and maintained backwater valves or homes with plumbing systems that are in poor condition. The city offers residents backwater valves inspection service free of charge in 18 boroughs.

Major debris

After a thunderstorm, residents can contact 311 to request an immediate response in the event of a tree branch that has fallen or is about to fall, or debris blocking a public road.

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