Ottawa Public Health has upgraded its heat advisory to a heat warning.
Humidex values are expected to exceed 40°C today and tomorrow.
Officials are telling residents to drink water and limit caffeine and alcohol consumption; Public Health suggests avoiding strenuous physical activity and direct exposure to the sun.
Dr. Carolyn Pim, Ottawa's associate medical officer of health, says if you want to check out the Canada Day festivities, you should be mindful of the heat.
"Try and seek shade when [you] can. Obviously, if it's sunny out and [you're] in the crowds, it's going to be difficult, but drink plenty of fluids," she told CFRA. "Watch for the signs; if you're sweating a lot, if you're feeling tired, you're getting muscle cramps, then that's the time to really get out of the heat and drink lots of fluids."
You're advised to spend at least two hours a day in an air-conditioned facility.
Officials are also asking that you keep an eye on those most vulnerable to the heat, including the elderly and children.