Thursday 10 July 2025 – Ottawa, Ontario (04:06 EDT)
Severe weather is once again taking aim at eastern Ontario and southern Quebec today, Thursday, as the active summer storm pattern continues to unfold across central Canada. Following a volatile Wednesday evening in southern Ontario, where parts of the region faced a tornado warning and localized rainfall totals above 50 mm, today’s threat is shifting eastward, bringing a fresh risk of intense thunderstorms.
Storm threat intensifies over eastern Ontario and southern Quebec
On Thursday afternoon and evening, eastern Ontario, including Ottawa and areas along the St. Lawrence River, such as Montreal and Quebec City, will be under the most favourable conditions for severe storms. These storms are expected to be widespread but scattered, capable of producing torrential downpours, hail measuring 2 to 4 centimetres in diameter, and damaging wind gusts.
Greater Toronto Area still under unsettled skies
The Greater Toronto Area (GTA), although no longer the centre of the storm activity, won’t be entirely in the clear. There remains a possibility for thunderstorm development, particularly where the Lake Ontario breeze interacts with the Niagara Escarpment and the Oak Ridges Moraine. These storms are not currently expected to meet severe criteria, but could still bring brief downpours and gusty winds.
St. Lawrence Valley at heightened flood risk
Significant atmospheric instability will grip the St. Lawrence Valley, extending northward into the Laurentians. Here, a combination of high humidity, instability, and slower-moving cells may lead to localized flooding, especially in low-lying areas and urban zones.
Storm activity possible inland from Lake Erie
Further inland from Lake Erie, conditions may also support storm development during the late afternoon and early evening, although the primary hazard in this region will be heavy rainfall rather than wind or hail.
Stay closely tuned to local weather alerts across Ontario and Quebec, as storm conditions can evolve quickly throughout the day.
