Environment Canada reported that the temperature hit 33 C at Pearson International Airport by noon on Thursday, with the humidity making it feel more like 42 C.
Thursday's heat followed two previous days in which the mercury hit 32 C or higher in Toronto.
The city has been under an extreme heat alert since Tuesday.
Eight city pools will be open for extended hours this evening, closing at 11:45 p.m., so that residents can have a chance to cool off if they choose.
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