Environment Canada has issued a heat warning for Collingwood, The Blue Mountains and most of Simcoe County.
Humidity is adding to daily maximum temperatures of 30 to 32 degrees, making the temperature closer to 37 to 42 degrees Celsius with the humidex.
Temperatures should drop to 18 to 21 degrees Celsius overnight.
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, heatstroke and the worsening of some health conditions.
The Simcoe Muskoka District Health Unit is urging caution during the extreme heat, recommending people drink lots of non-caffeinated fluids and stay cool indoors where possible.
If you are outdoors, stay in the shade and re-apply sunscreen often. Make sure to wear a broad-brimmed hat, sunglasses, and lightweight clothing.
During extreme heat warnings, the health unit advises to keep physical activity to a minimum.
For more from the health unit, visit smdhu.org.
