The temperature is expected to reach 33 C in Toronto, but with the humidex it could feel more like 37, an Environment Canada heat warning forecasts.

In a heat warning issued Tuesday morning, the weather agency said a hot air mass that moved into the region on Monday continues to hover over southern Ontario. Daytime highs in the low- to mid-30s can be expected until the mass passes on Thursday. Overnight low temperatures are expected to stay a few degrees shy of the heat warning threshold of 30 C.

Residents of the affected areas are warned to watch for symptoms of heat illness including dizziness and fainting, headache, rapid breathing and decreased urination. Anyone who experiences the symptoms is advised to move to a cool place and drink liquids.

  • Toronto
  • Niagara
  • Hamilton
  • Halton-Peel
  • York-Durham
  • Belleville-Quinte
  • Kingston-Prince Edward
  • Stirling-Tweed-South Frontenac
  • Brockville-Leeds and Grenville
  • Ottawa-Gatineau
  • Prescott and Russell
  • Cornwall-Morrisburg
  • Smiths Falls-Lanark-Sharbot Lake