Canada, US: Heatwave forecast across parts of southeastern Canada and the northeastern US through at least June 21

High temperatures are forecast across parts of southeastern Canada and the northeastern US through at least June 21. The affected area includes New Brunswick, eastern and southern Ontario, southern, south-central, and western Quebec in Canada, and parts of the Ohio Valley and Northeast regions in the US. Temperatures of 29-38 C (84-100 F) are expected across much of the region over the coming days, with localized higher maximums.

As of early June 17, Environment Canada has issued red (highest level on a three-tier scale) heat warnings across New Brunswick, eastern and southern Ontario, and southern and western Quebec. Grey special weather statements for high temperatures are in place across south-central Quebec.

The US National Weather Service (NWS) has issued excessive heat warnings for parts of northeastern Indiana, northwestern Ohio, and southeastern Michigan. Excessive heat watches have been issued for parts of northern Connecticut and central and eastern Massachusetts. Heat advisories are in place across the rest of the affected area in the US.

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 speeds. 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.