The Greater Toronto Area (GTA) is bracing for a significant heatwave between July 13 and 15, 2026, with humidex values expected to reach nearly 40°C. According to forecasts reported by the Korea Times, the peak of the heat will occur on Tuesday, July 14, when daytime highs are projected to hit 34°C.
Daily Temperature Forecast for the GTA Heatwave
Weather patterns for the second week of July indicate a sharp rise in temperature followed by a return to seasonal norms. According to the Korea Times, the heat will intensify over a three-day window:
- Monday, July 13: Daytime highs will reach approximately 30°C, with the “feels-like” temperature approaching 40°C.
- Tuesday, July 14: This marks the peak of the event, with expected highs of 34°C and humidex values nearing 40°C.
- Wednesday, July 15: Temperatures will remain elevated with a projected high of 32°C.
The heat is expected to break by Thursday, July 16, as temperatures drop below 30°C and return to typical July averages, the report states.
Understanding Humidex and Heat Risk
The gap between the actual temperature (34°C) and the perceived temperature (40°C) is driven by humidity. In Canada, Environment and Climate Change Canada uses the Humidex scale to describe how humidity affects the human body’s ability to cool itself through perspiration. When humidity is high, sweat doesn’t evaporate as quickly, making the air feel significantly hotter than the thermometer indicates.
A humidex value of 40°C is generally categorized as a point where heat stress becomes a serious concern for the general population, particularly for seniors, children, and those with pre-existing health conditions.
Comparing the Heat Peak
| Date | Forecast High | Perceived Temp (Humidex) |
|---|---|---|
| July 13 | ~30°C | Near 40°C |
| July 14 | 34°C | Near 40°C |
| July 15 | 32°C | Elevated |
Heat Safety and Prevention
To manage the risks associated with a 40°C humidex, health authorities typically recommend several immediate actions. Residents should increase water intake regardless of thirst and seek air-conditioned environments. The Public Health Agency of Canada emphasizes avoiding direct sunlight during the peak hours of 11 a.m. to 4 p.m. and monitoring for signs of heat exhaustion, such as heavy sweating and dizziness.
As the GTA prepares for this temperature spike, the forecast suggests a brief but intense window of extreme humidity before a cooling trend begins on July 16.