Toronto is bracing for a weekend of intense weather, marked by oppressive heat, unbearable humidity and a growing risk of thunderstorms. As of Friday, July 5, the atmosphere over Southern Ontario is already heating up, and a dramatic shift is expected by Monday.
Friday brings classic summer sun and high UV
This Friday, the city is enjoying a quintessential summer day, with clear skies, a high of 27 °C (81 °F) and a humidex of 32 °C (90 °F). The UV index is rated at 9, considered very high, demanding maximum sun protection. The evening hours bring a welcome cool down, with temperatures dropping to 17 °C (63 °F) under clear skies—ideal for a late walk or night out.
Saturday’s heat pushes the limit with a humidex of 41
By Saturday, July 6, the heat intensifies significantly. The afternoon high is forecast at 31 °C (88 °F), but with humidity soaring, it will feel closer to 41 °C (106 °F). The air mass will be thick and muggy, and clouds will start to build during the morning hours, bringing a 30% chance of showers and a risk of thunderstorms by the late afternoon.
Winds from the south, around 20 km/h, will add to the unstable air, though not enough to provide real relief. The night remains sticky, with overcast periods and a low of 20 °C (68 °F), maintaining the sultry atmosphere well past sunset.
Sunday continues the heat before storms ramp up
On Sunday, July 7, Toronto wakes up to a mix of sun and cloud, but the heat doesn’t let up. Temperatures will again reach 31 °C (88 °F), maintaining that oppressive feel across the region. By the evening, a 40% chance of showers could disrupt outdoor plans, particularly around sunset.
Monday shifts to cooler, stormier conditions
Come Monday, July 8, the pattern breaks. Though skies will stay mostly cloudy, cooler air will settle in. The high will be more manageable at 24 °C (75 °F), though the risk of precipitation rises to 60% throughout the day. Overnight, the chance of rain holds at 40%, with temperatures dipping to 17 °C (63 °F)—signalling the end of the heatwave conditions for now.
Storms, heat, and unpredictable skies will define this weekend across Toronto and the GTA. The humidity will be relentless, and conditions could change quickly, especially as moist southern air collides with local systems.
