An intense weather system is moving through southern Ontario, bringing strong thunderstorms, heavy rainfall, and a surge in humidity, with the humidex reaching values in the mid-30s°C (mid-90s°F). A severe thunderstorm watch has been issued by Environment Canada on Wednesday, as waves of showers and storms move ahead of a cold front expected to arrive on Thursday.
Rainfall warnings in effect for Bruce, Brant and Haldimand counties
Bruce, Brant, and Haldimand counties are under rainfall warnings. These areas could see an additional 40 to 60 millimetres of accumulated precipitation, which may lead to localized flooding and poor drainage in vulnerable zones.
The air mass remains highly humid until the cold front pushes through on Thursday. As CTV London meteorologist Julie Atchison explained, “This is a tropical air mass,” with conditions that have felt “like the mid-30s°C (mid-90s°F).”
Wednesday night: unsettled skies with thunderstorm risk
Through Wednesday evening, skies will be cloudy, with a 40% chance of showers early in the evening. These will evolve into showers or scattered thunderstorms, which will then taper off to a 40% chance of showers near midnight. There’s a continued risk of thunderstorms overnight, with winds shifting from southeast at 20 km/h to southwest at 20 km/h, gusting up to 40 km/h. The temperature will hold steady near 18°C (64°F).
Thursday: scattered showers and stronger winds
Thursday will remain cloudy, with a 60% chance of showers. Winds will blow from the southwest at 20 km/h, gusting to 40 km/h, becoming northwest at 30 km/h, with gusts up to 50 km/h in the afternoon. The high will be 22°C (72°F), with a humidex of 25°C (77°F). The UV index will be moderate, at 4.
Friday: mix of sun and cloud with chance of showers
On Friday, expect a mix of sun and cloud, with a 30% chance of light showers. The temperature will rise to 27°C (81°F), with more comfortable and less humid conditions compared to earlier in the week.
Weekend outlook: sunshine and summer warmth
Saturday will bring sunny and breezy conditions, with a daytime high reaching 29°C (84°F). Expect stable weather ideal for those heading toward Lake Ontario or across the Golden Horseshoe.
On Sunday, clear skies will continue, with the temperature peaking at a hot 33°C (91°F).
