Another heat wave hangs over southern Ontario
Posted Jul 11, 2025 11:57:43 AM.
Last Updated Jul 14, 2025 10:35:05 AM.
Another summer heat wave is expected to bring scorching temperatures to southern Ontario for about a week.
Environment Canada has issued a heat warning for Waterloo Region as hot and humid conditions will arrive Friday and could persist into Thursday.
Daytime highs between 29 and 32 C are in the forecast, with humidex values between 35 and 40.
There won’t be much relief overnight either, with projected lows of 23 to 19 C.
Carl Lam, 570 meteorologist, said the heat warning now has the potential to go to Thursday instead of Wednesday.
“We’re still wrapped in all that heat and humidity and Wednesday into Thursday is going to be an active situation with rain showers and thunderstorms,” said Lam. “This is going to be a mechanism to kind of clear out the humidity across the tri-cities.”
The national weather agency says people should take precautions. That includes limiting your time outdoors, staying hydrated, watching out for signs of heat exhaustion, and checking in on vulnerable friends, family and neighbours.
Regional cooling centres will be available, and you can find the complete list by clicking here.
