Science

Toronto Flood Timeline: Major Floods & Climate Risk

Toronto floods because intense rainfall can overwhelm rivers, creeks, roads, sewers, basements and stormwater systems, especially in low-lying or heavily paved…

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SEPTEMBER 2026 STORM

Storm Closes the Don Valley Parkway, Cuts Power to 45,000

A powerful storm brought large hail, destructive winds and tornado warnings on September 2, 2026, flooding and closing the Don Valley Parkway and several other roads. To…

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NATIONAL FLOOD-RISK WARNINGS

Insurers Warn Flood Risk Is Rising Across Canada

No single Toronto event defined 2025, but national severe-weather insured losses topped $2.4 billion, the 10th costliest year on record. About 10% of Canadian households…

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JULY 2024 FLASH FLOOD

Flood Submerges the DVP and Billy Bishop Tunnel

Torrential rain on July 15-16, 2024 flooded the Don Valley Parkway and closed Billy Bishop Airport's pedestrian tunnel. About 167,000 Toronto Hydro customers lost power;…

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RECORD RAINFALL

126mm Storm Breaks Toronto's One-Day Rainfall Record

A severe storm dropped 126mm of rain at Pearson Airport on July 8, 2013, breaking Hazel's 1954 record. More than 300,000 lost power and about 1,400 GO Transit passengers…

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2005 GTA RAINSTORM

Finch Avenue West Washes Out

A storm dropped about 103mm of rain on August 19, 2005, washing out a roughly 30-metre section of Finch Avenue West and flooding thousands of basements. Insurers receive…

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URBAN EXPANSION

Urban Growth Adds New Flood Pressure

Toronto's rapid expansion added far more paved surfaces across the region. More hard surfaces mean rainfall runs off faster into drains, creeks and rivers instead of soa…

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FLOODPLAIN POLICY

Floodplains Become Protected Land

In the years after Hazel, the province merged local conservation bodies into what became the Toronto and Region Conservation Authority, converting former floodplain neig…

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HURRICANE HAZEL

Hurricane Hazel Kills 81, Redefines Flood Policy

Hurricane Hazel struck Toronto on October 15-16, 1954, dropping over 200mm of rain in 24 hours. The Humber River widened from 65 feet to 350 feet at Woodbridge. The stor…

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