Residents across Montreal’s West Island spent Sunday clearing flood-damaged homes and discarding ruined belongings after severe thunderstorms dropped between 100 and 170 millimetres of rain in just two hours on Saturday, June 20, 2026. The storm triggered flash flooding that overwhelmed sewer systems, left hundreds without power, and affected properties that had never previously experienced water damage, according to Pierrefonds-Roxboro borough mayor Jim Beis and reports from local homeowners.
What caused the widespread flooding?
The flooding was driven by an extreme volume of rainfall concentrated into a short two-hour window, which exceeded the capacity of municipal storm sewer systems. According to Pierrefonds-Roxboro mayor Jim Beis, this intensity created conditions that were “impossible to prepare for,” as water levels reached up to four feet on some streets. The City of Montreal has stated that climate change is contributing to these increasingly intense rainfall episodes, which can overload infrastructure and force water onto streets and private property.
Did You Know? While some residents in Pierrefonds have faced repeated flooding, including those who have sandbagged their homes during previous storms, Mayor Jim Beis noted that this specific event affected many homeowners for the first time, marking a shift in the scale of impact compared to previous years.
Current status of recovery efforts
As of 8 p.m. Sunday, roughly 700 Montreal-area addresses remained without power, a significant improvement from the 20,000 households affected at the height of the storm on Saturday evening, according to Hydro-Québec. Residents spent the day documenting damage for insurance claims and clearing debris, such as water-logged drywall, furniture, and personal items, from their basements. In Dollard-des-Ormeaux, residents like Barbara Frost reported that water entered homes through basement drains and garage seepage, causing extensive damage to floors and walls.
Expert Insight: The distinction between this weekend’s flash flooding and typical spring runoff is critical for homeowners. While municipal barriers and pumps have proven effective against river backflow from the Rivière des Prairies, current storm sewer designs are not equipped to handle such high-velocity, localized downpours. This suggests a potential shift in risk assessment for suburban homeowners, moving from river-proximity concerns to a broader vulnerability tied to municipal drainage capacity during extreme weather.
What happens next?
Environment Canada continues to monitor the region for further weather risks. While a severe thunderstorm warning for areas including Pierrefonds, Dollard-des-Ormeaux, and parts of Laval was lifted by 3 p.m. Sunday, the agency warned that the ground remains saturated and has a reduced ability to absorb additional rainfall. Officials, including Mayor Beis and Domestic Security Minister Ian Lafrenière, are expected to continue discussions regarding government support and the implementation of waterproofing tools for residential properties, such as specialized driveway barriers.
Frequently Asked Questions
Was this flooding caused by the Rivière des Prairies?
No. According to Pierrefonds-Roxboro mayor Jim Beis, Saturday’s flooding is distinct from spring flooding caused by river backflow. It was caused by extreme rainfall that overwhelmed the local storm sewer system.
How many people lost power?
At the peak of the storm on Saturday evening, 20,000 Hydro-Québec customers were without power. By 8 p.m. Sunday, that number had decreased to approximately 700 addresses.
Are there any warnings still in effect?
The severe thunderstorm warning issued Sunday afternoon was lifted by 3 p.m. However, Environment Canada had previously issued a severe thunderstorm watch for the island of Montreal, noting that conditions remained favorable for repeated showers that could cause further flash flooding.
How have you and your neighbors managed the cleanup process following this weekend’s heavy rainfall?
