Niagara is under a heat warning.
Environment Canada says heat and humidity are expected to continue today and possibly through to the middle of this week.
Daytime maximum temperatures will be between 30 to 32 degrees, with humidex values of 37 to 40.
At night it will remain warn near 21 degrees.
Hot and humid air can also bring deteriorating air quality and can cause the Air Quality Health Index to approach the high risk category.
Extreme heat affects everyone.
The risks are greater for young children, pregnant women, older adults, people with chronic illnesses and people working or exercising outdoors.
Watch for the effects of heat illness: swelling, rash, cramps, fainting, heat exhaustion, heat stroke and the worsening of some health conditions.
Never leave people or pets inside a parked vehicle.
Heat warnings are issued when very high temperature or humidity conditions are expected to pose an elevated risk of heat illnesses, such as heat stroke or heat exhaustion.