7:07 p.m. EDT Wednesday 23 July 2025

Heat Warning in effect for:

• City of Toronto

A heat event is expected to begin Thursday.

Thursday:
Daytime high temperatures up to 35 degrees Celsius.
Peak humidex values up to 44.
Nighttime low temperatures of 20 to 23 degrees Celsius, providing little relief from the heat.

Friday:
Daytime high temperatures near 30 degrees Celsius.
Peak humidex values near 40.
Nighttime low temperatures near 21 degrees Celsius, providing little relief from the heat.

When:
Thursday and Friday. Possibly continuing through the weekend for some areas.

Additional information:
The hottest conditions are expected on Thursday. While daytime high temperatures will not be as extreme on Friday and into the weekend, nighttime lows are expected to remain warm throughout.

Take action to protect yourself and others – extreme heat can affect everyone’s health. Determine if you or others around you are at greater risk of heat illness. Check on older adults, those living alone and other at-risk people in-person or on the phone multiple times a day.

Watch for the early signs of heat exhaustion in yourself and others. Signs may include headache, nausea, dizziness, thirst, dark urine and intense fatigue. Stop your activity and drink water.

Heat stroke is a medical emergency! Call 9-1-1 or your emergency health provider if you, or someone around you, is showing signs of heat stroke which can include red and hot skin, dizziness, nausea, confusion and change in consciousness. While you wait for medical attention, try to cool the person by moving them to a cool place, removing extra clothing, applying cold water or ice packs around the body.

Drink water often and before you feel thirsty to replace fluids.

Close blinds, or shades and open windows if outside is cooler than inside.

Turn on air conditioning, use a fan, or move to a cooler area of your living space. If your living space is hot, move to a cool public space such as a cooling centre, community centre, library or shaded park.

Follow the advice of your region’s public health authority.

Plan and schedule outdoor activities during the coolest parts of the day.

Limit direct exposure to the sun and heat. Wear lightweight, light-coloured, loose-fitting clothing and a wide-brimmed hat.

Never leave people, especially children, or pets inside a parked vehicle. Check the vehicle before locking to make sure no one is left behind.

For more information: https://www.canada.ca/en/health-canada/services/climate-change-health/extreme-heat/how-protect-yourself.html https://www.canada.ca/en/health-canada/services/climate-change-health/extreme-heat/who-is-at-risk.html

Please continue to monitor alerts and forecasts issued by Environment Canada. To report severe weather, send an email to ONstorm@ec.gc.ca or post reports on X using #ONStorm.