June 24 weather: High that feels over 40 C and thunderstorm risk in southern Ontario

It could feel warmer than 40 C on Tuesday with a heat warning in effect and a risk of thunderstorms in the Greater Toronto Area and southern Ontario.

Environment Canada says the heat warning is expected to last into Tuesday with daytime temperatures reaching 33 C in the GTA.

But it could feel between 40 to 43 C with the humidity in Toronto, Mississauga, Hamilton, Pickering, Oshawa and Niagara Falls.

Conditions will be mainly sunny with a 30 per cent chance of showers in the afternoon, followed by a risk of thunderstorms across southern Ontario, the weather agency says.

Winds could be gusting up to 50 km/h in the afternoon.

Into the evening, conditions are expected to cool a bit with cloudy skies and a low around 20 C.

Environment Canada says the “dangerously hot and humid conditions” could lead to health issues, and says to watch for signs of heat exhaustion in yourself and others.

“Signs may include headache, nausea, dizziness, thirst, dark urine and intense fatigue. Stop your activity and drink water,” Environment Canada says.

“Check on older adults, those living alone and other at-risk people in-person or on the phone multiple times a day.”