Southern Ontario, thunderstorms and heat wave

Severe thunderstorms to sweep across Ontario Thursday. A combination of a frontal boundary and heavy atmospheric moisture could lead to heavy rainfall and localized flooding. The primary hazards associated with these storms are heavy rain, large hail, and potentially damaging winds. Residents are urged to remain vigilant as conditions evolve.

Severe storms are forecast to begin near the Lake Huron shoreline around 11 a.m., reaching the Greater Toronto Area (GTA) by 1–2 p.m. Impacts to major highways (401, 404, and 400) are anticipated.

A significant U.S. heat wave into Canada this weekend

Major urban centers like Toronto, Windsor, and Ottawa should anticipate temperatures over 30°C by Monday, with humidity pushing "feels-like" temperatures close to 40. These values are about 5°C above seasonal norms.

Last heat wave saw temperatures peak at 36°C, with a maximum humidex reading of 48.

Environment Canada