The southern and northern regions can expect humidex values around 40 degrees for the next three days.
Environment Canada says hot and humid conditions can be expected throughout the week.
Tomorrow and Thursday, daytime temperatures will be around the high 20s to low 30s, combining with high humidity to result in humidex values near 40 degrees.
The humidex is may also be around 40 on Friday, but cooler and less humid air is expected in time for the weekend.
You're advised to schedule outdoor activities for the cooler parts of the day, drink plenty of water and stay in a cool place.
Young children, pregnant women, senior citizens, people with chronic illnesses and anyone working or exercising outdoors face the greatest risks.