Canada wildfire smoke triggers heat wave and poor air quality warnings in Toronto and the GTA; check who are at risk

As the wildfire smoke from forest fires over northern Ontario causes the air quality to deteriorate, Environment Canada has placed Toronto and the surrounding GTA under both a heat wave and a poor air quality warning. The weather agency issued the warning in the early hours on Monday, July 14, 2025.

The agency stated that the smoke from forest fires over northern Ontario moving into the area is causing the air quality to deteriorate. According to local media reports, the poor air quality is expected to persist from Monday into Tuesday.

The weather agency also stated that the smoke from wildfires in forests and grasslands can be a major source of air pollution for people in Canada. An advisory has also been issued for much of central Ontario, including Barrie, Orillia, Midland, Gravenhurst, and Huntsville, according to CTV News


“During heavy smoke conditions, everyone’s health is at risk regardless of their age or health status. Limit time outdoors. Reschedule or cancel outdoor sports, activities, and events,” Environment Canada said, as quoted by Global News

Heat warning in Toronto

Meanwhile, a heat warning has been issued for Toronto as a prolonged period of extreme heat and humidity continues to persist. As far as the mercury in the region is concerned, the weather agency has said that daytime highs are expected to reach as high as 32°C, with humidex values of 35 to 40. Overnight lows of 19°C to 23°C will give minor relief from the warm temperatures.

According to Environment Canada, the heat wave is expected to continue until Thursday. “A shift in the weather pattern late this week will likely end this multi-day period of heat and humidity Thursday night,” the alert read, according to Global News.

Residents urged to take precautions

As the wildfire smoke hampers air quality, residents are urged to take precautions. All citizens, especially seniors, children, pregnant women, outdoor workers, and those with chronic health conditions, like asthma or heart disease, are the most vulnerable and are asked to remain extra cautious, CTV News.

The national weather agency has warned that people may notice mild symptoms such as irritated eyes, sore throats, headaches, or coughs. If things turn severe, people may also face difficulty in breathing or chest pain. In such a condition, they have been advised to seek medication.

"When indoors, keep windows and doors closed as much as possible. When there is an extreme heat event occurring with poor air quality, prioritize keeping cool," Environment Canada’s air quality statement reads. People have also been urged to consider cancelling or rescheduling outdoor events due to the air quality on Monday.