Be prepared for "exceptionally" hot and humid conditions in Windsor-Essex and Chatham-Kent Wednesday, according to Environment Canada.
In a special weather statement, the agency said that daytime temperatures are predicted to reach a high of 34 C Wednesday, with the humidex value expected to reach 45.
Overnight, temperatures are expected to drop to 23 C, but Environment Canada said that will "provide minimal relief from the heat."
A cold front is expected to pass through on Thursday and bring temperatures back down.
Despite the high temperature for Wednesday, Environment Canada said it will not issue a heat warning as that requires hot and humid conditions to last for two days, including an overnight low in between to be 21 C or higher.
But it said that the conditions can still pose a health risk, which is why it has issued a special weather statement.
Environment Canada reminded people to check in on older family, friends and neighbours and to never leave people or pets inside a parked vehicle.
"Hot and humid air can also bring deteriorating air quality and can result in the Air Quality Health Index approaching the high risk category," reads the statement.
In a news release Tuesday, the Windsor-Essex County Health Unit (WECHU) said warning signs of heat-related illness include dizziness, headache, nausea or vomiting, weakness and confusion.
Anyone who experiences these symptoms should seek medical attention, the WECHU said.
When it comes to staying cool, the health unit said to follow these tips:
Drink a lot of water, even if you don't feel thirsty.
Wear a wide-brimmed hat and lightweight, loose-fitting clothing.
Take a cool bath or shower.
Limit outdoor activities to the coolest part of the day.
Look for shade or a cool shelter in an air-conditioned location.
Learn about ways to keep your home cool, like adding window shades drawn to prevent sun from coming in.