Environment Canada has placed a yellow heat warning over the Greater Toronto Area beginning Monday, July 13, 2026 and lasting through Thursday, July 16, 2026. The advisory follows the agency’s assessment of an approaching heat wave that will bring both high temperatures and elevated humidity across the region.
The warning highlights that humidex values are expected to near 45 °C during the period, a level that signals uncomfortable and potentially hazardous conditions. On Tuesday, the forecast calls for a peak temperature of 37 °C, contributing to the high humidex reading that combines heat and moisture to express how hot it feels.
A yellow heat warning is the first tier of heat advisories used by Environment Canada. It indicates that weather conditions are likely to be uncomfortable for many people, especially those who are sensitive to heat, and that the public should be aware of the increased risk of heat‑related stress. The advisory does not carry the same severity as a red warning, but it serves as an early alert to prepare for the anticipated warmth.
The heat wave is expected to affect the entire GTA, with the combination of temperature and humidity creating a feeling of intense heat that can be more demanding than temperature alone would suggest. Residents across Toronto, Mississauga, Brampton and surrounding municipalities will experience the same advisory period, as the warning applies to the whole Greater Toronto Area.
Environment Canada’s issuance of the yellow heat warning underscores the agency’s monitoring of the upcoming weather pattern and its impact on public health and comfort. The agency will continue to update forecasts and may adjust the advisory level if conditions change. The public is encouraged to stay informed through official channels as the heat wave progresses through the middle of the week.