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4 clusters · 10 sources · 27 days · First seen · Last updated

Ontario multi-day thunderstorm and flood risk

Overview

Late July 2026 saw Environment Canada lift a yellow severe thunderstorm watch for southwestern Ontario, warning that heavy rain could exceed 50 mm and raise flood risk from the Greater Toronto Area northward to Georgian Bay. Early August brought the forecasted thunderstorms, prompting special weather statements and rainfall warnings for the GTA, Niagara Region and cottage-country communities, with expected totals of 50-80 mm.

The threat materialised over the August 1-2 weekend. Record rainfall fell across southern Ontario: the Quinte region received up to 80 mm, while the Niagara Peninsula saw localized totals above 100 mm and St. Catharines recorded 257.7 mm in the preceding week. Rivers peaked, prompting Quinte Conservation to operate watershed dams and issue water-safety advisories. St. Catharines declared a state of emergency on August 3 due to damage to homes and infrastructure. A brief tornado warning was issued in the Niagara region, with minor tree damage reported in Kemptville.

In late August, a new slow-moving weather system prompted further alerts. The Niagara Peninsula Conservation Authority issued a flood alert for the Niagara Peninsula, southeastern Hamilton, and eastern Haldimand County, forecasting 40 to 60 mm of rain between August 22 and August 24. While major flooding in large watercourses was not anticipated, officials warned of flash flooding in urban areas. Simultaneously, Environment Canada issued a special weather statement for Toronto, expecting heavy rain exceeding 50 mm and two rounds of thunderstorms.

Entities

Environment Canada · Ontario · Niagara Peninsula · Toronto · Chatham‑Kent

Timeline

  1. 1 day ago

    [INTERNATIONAL] 4 sources
    Ontario weather alerts issued for heavy rain and potential flooding

    Heavy rain and thunderstorm warnings have been issued for Toronto and the Niagara Peninsula in Ontario, with officials warning of potential flash flooding and localized heavy rainfall.

  2. 20 days ago

    [INTERNATIONAL] 3 sources
    Ontario declares state of emergency amid record rainfall

    Ontario faced record rain in early August 2026, with up to 80 mm in the Quinte region and over 100 mm in the Niagara Peninsula, prompting a state of emergency in St. Catharines and a water‑safety alert from Qui

  3. 21 days ago

    [POLITICS] 2 sources
    Heavy Rain and Thunderstorms Prompt Special Weather Statement for Greater Toronto Area

    Environment Canada warned that heavy rain and thunderstorms could bring up to 50 mm of rain in the Greater Toronto Area and Niagara Region, prompting flood and driving safety alerts.

  4. 27 days ago

    [INTERNATIONAL] 3 sources
    Ontario faces multi‑day thunderstorm risk and flood warnings

    Environment Canada lifted a thunderstorm watch for southwestern Ontario and warned of multi‑day storms and heavy rain that could cause flooding across southern Ontario through early August.

Sources

680news.com · ca.news.yahoo.com · chinesepress.com · cknewstoday.ca · eawaz.com · inquinte.ca · niagaraatlarge.com · quintenews.com · toronto.citynews.ca · whec.com

This summary has been updated 2 times: see revision history