Canada: Heatwave forecast across northern Ontario and southern and central Quebec through Aug. 2

High temperatures are forecast across northern Ontario and southern and central Quebec through at least Aug. 2. As of late July 28, authorities have issued red (highest level on a three-tier scale) heat warnings across northern Ontario and west central Quebec; temperatures of around 29-33 C (84-91 F) with overnight lows of around 17-20 C (62-68 F) are likely. The high temperatures over northwestern Ontario are forecast to ease late July 28 and over northeastern Ontario and west central Quebec July 30. Grey special weather statements for high temperatures are in place across the rest of the affected area through Aug. 2. Humidex values of 35-39 C (95-102 F) are forecast July 29-30, with a brief break in the heat July 31 due to scattered showers, before the high temperatures and humidity return Aug. 1-2. Officials could update and possibly extend the coverage of weather alerts over the coming days.

The high temperatures may result in increased energy and water demand, and a heightened risk of heat-related illnesses, such as heat exhaustion and heat stroke. Authorities advise the general public to avoid prolonged exposure to direct sunlight, wear loose and light clothing, and stay hydrated.

The extended period of oppressive heat and dry conditions may produce ideal circumstances for wildfire growth throughout the region. Heatwaves also pose a threat to vulnerable groups - such as the elderly, children, pregnant women, and those with respiratory illnesses - due to the increased possibility of heat stroke or heat exhaustion during prolonged exposure to high temperatures. These health risks could also extend to relatively healthy individuals during significant heatwave events.

Very high temperatures may warp rail tracks and force passenger and freight trains to operate at reduced speed. Road surface damage is also possible, and overheated vehicles may worsen traffic problems in urban areas where congestion is already a problem. Commercial trucking disruptions might occur as very high temperatures stress vehicles, making tire blowouts more common. Major flight disruptions are unlikely, but general aviation disruptions are possible, and some airfreight carriers could reduce cargo loads. High temperatures could lead to an increased demand for electricity, which might trigger localized brownouts or blackouts, exacerbating hazardous conditions when air conditioning is no longer possible.