A multi-day heat event is underway across much of Ontario, with Environment Canada warning that temperatures could climb as high as 37 C and humidex values reach 45.
The hot weather is expected to continue through Wednesday or Thursday, with Tuesday forecast to be the hottest day of the stretch. Overnight lows will offer little relief, remaining between 20 and 24 C.
The weather agency says the extreme heat could also worsen air quality, with the Air Quality Health Index potentially reaching high-risk levels.
Residents are urged to drink plenty of water, limit strenuous outdoor activity, and check regularly on older adults, those living alone and others at greater risk of heat-related illness.
Officials say symptoms of heat exhaustion include headache, dizziness, nausea, intense fatigue and dark urine. Anyone showing signs of heat stroke, including confusion, hot skin or loss of consciousness, should receive immediate medical attention by calling 911.
