Strong winds and heavy rain return to Southern Ontario
OTTAWA, Saturday, July 19, 2025 (3:34 p.m. EDT) – After a brief mid-July reprieve, Southern Ontario is once again bracing for severe thunderstorms as a low-pressure system advances over the Great Lakes. The system is expected to ignite widespread storm activity across Southern Ontario and parts of cottage country, beginning Saturday afternoon and continuing into the overnight hours.
A sharp transition from calm to chaos
The dry, comfortable air that moved in on Thursday and Friday gave residents a break from the oppressive humidity. But the atmosphere is primed for a shift. A warm front, surging northward across Ontario, is helping to set the stage for unstable conditions, particularly in areas stretching from Muskoka to Sarnia.
As the day progresses, thunderstorms are forecast to form over the U.S. Midwest, then track northeastward toward Southern Ontario. By late Saturday afternoon, storm clusters may begin to impact regions along the shores of Lake Huron and Georgian Bay. The primary threats include strong wind gusts and torrential rainfall, both capable of causing localized flooding and power disruptions.
Greater Toronto Area could be hit overnight
While it’s uncertain how potent these storms will remain once they reach the Greater Toronto Area (GTA), residents can still expect frequent lightning, intense downpours, and brief but powerful wind gusts. Storm activity is likely to arrive in the GTA by late evening or overnight.
Unlike recent storm systems, humidity levels aren’t expected to be as intense. As a result, rainfall totals will likely remain within the 10 to 30 mm range (approximately 0.4 to 1.2 inches) in most affected areas. However, pockets of heavier precipitation are possible, particularly under the most intense storm cells.
Warm but unsettled weather continues Sunday
As Saturday night’s system departs, Sunday should bring calmer and more pleasant conditions, although isolated showers could linger into the morning. Temperatures will stay close to seasonal averages, hovering in the mid-to-upper 20s°C (around 77–84°F), with a light return of humidity during the day.
The Weather Network will continue to provide updates as the situation evolves. Stay alert for weather advisories and keep an eye on local radar to track storm development in your area.
