Environment Canada says daytime highs between 30 and 33 degrees Celsius likely tomorrow, with humidex values around 40.
You may want to stay indoors tomorrow and Thursday.
A heat warning has been issued for Niagara.
The weather office says beginning tomorrow afternoon, daytime highs are expected to reach 30 to 33 degrees Celsius, with humidex values near 40.
Overnight lows will range from 20 to 22 degrees.
Hot and humid conditions will remain in effect into Thursday, but showers and thunderstorms may bring slightly cooler temperatures to some areas.
Conditions are expected to improve on Thursday evening.
The risks of extreme heat are greatest for young children, pregnant women, seniors, people with chronic illnesses and anyone who works or exercises outdoors.
Environment Canada also reminds you not to leave pets or children inside a parked car.
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