A quick look at the humidex numbers explains why they are taking this precaution.
The combination of high temperatures and high humidity can have serious effects on residents, and can lead to heat stroke.
Heart related illnesses and breathing difficulties can be exacerbated in these conditions.
Symptoms include rapid breathing, dizziness or even fainting.
The Chatham-Kent Health Unit advises you to avoid extended exposure to the heat, remain in cool areas drink plenty of water, and seek immediate medical attention if you feel any of the symptoms.
The elderly, children, and people with chronic illnesses are most at risk.
This heat warning will be in effect until Wednesday.