Tornadic storm threat shifts to Ottawa, southern Quebec Tuesday
A multi-day severe weather event continues to unfold across Ontario and Quebec. A heat dome to the south is driving a "ring of fire" pattern, increasing the risk of torrential rain, damaging winds, large hail, and the potential for tornadoes in some regions
A persistent heat dome affecting Ontario is causing temperatures to soar into the 30s, with humidex values reaching the 40s across northern regions on Monday and Tuesday. This extreme heat is worsening fire weather conditions in northwestern Ontario, where over 100 wildfires continue to burn.
Severe thunderstorms, fuelled by this heat dome’s outer edge—a phenomenon often referred to as the "ring of fire"—began to develop Monday and are expected to persist through the overnight and Tuesday. Some of the pre-dawn storms on Tuesday could become severe.
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Residents across both Ontario and Quebec should monitor alerts, and be prepared for potential severe weather impacts including damaging winds, torrential downpours, and an isolated tornado.
Tuesday: Severe thunderstorm risk for Ottawa region, St. Lawrence, and southern Quebec
High-impact, active weather is forecast to continue into Tuesday afternoon, with eastern Ontario, the St. Lawrence region, and southern Quebec—including Ottawa and Montreal—at risk for severe thunderstorms.
A frontal boundary is expected to trigger widespread storm development north of the St. Lawrence and the National Capital Region. These storms are forecast to spread into the Eastern Townships and parts of eastern Ontario by the evening.
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Key risks include large hail, heavy downpours, and damaging wind gusts over 110 km/h. Forecasters are also closely watching the risk for a few tornadoes to spin up in some of these evening storms, as they will be developing in a dangerous environment with lots of spin in the atmosphere.
Stay updated with the latest weather alerts and forecasts as conditions evolve throughout the coming day.