A heat warning has been issued for: City of Toronto, City of Hamilton, Mississauga - Brampton, Burlington - Oakville, St. Catharines - Grimsby - Northern Niagara Region.
Environment Canada says a very warm airmass is expected to affect the Golden Horseshoe Sunday and Monday.
Highs near 31 degrees celsius and lows near 20 degrees celsius are expected.
This event is expected to be mainly confined to urban areas where minimum temperatures will be highest.
The heat event is expected to end on Monday night when a cooler airmass moves into the region.
Environment Canada reminding people that hot and humid air can also bring deteriorating air quality and cause the air quality health index to approach the high risk category.
The risks are greater for young children, pregnant women, older adults, people with chronic illnesses and people working or exercising outdoors.
You're advised to watch for the effects of heat illness: swelling, rash, cramps, fainting, heat exhaustion, heat stroke and the worsening of some health conditions.
An interactive map is available online to help those who need to access a cool space find a location near them: https://t.co/JYygSfOqkm.
— City of Toronto (@cityoftoronto) August 22, 2020