Extreme Heat

When the weather gets too hot, it can harm your health. By learning how to stay safe during extreme heat, you can protect yourself and your loved ones. This page will guide you through what to do when heat warnings are issued, how to cool down, where to find cooling centres, and what to do if you or someone you know shows signs of heat-related illnesses.

How do you know when a heat warning is issued?

Southwestern Public Health (SWPH) issues heat warnings to help you prepare for dangerous temperatures:

• Heat Warning: Daytime temperatures reach 31°C or higher and nighttime temperatures are 20°C or higher for at least two days, or when it feels like 40°C or hotter for two days.

• Extended Heat Warning: The same conditions but lasting three or more days.

You’ll find heat warnings on our website, social media, and in local news. Child care centres and community partners also get updates. Be a role model by practising sun and heat safety behaviour for children to see.

How can you stay safe in the heat?

When it’s hot, simple steps can make a big difference:

• Drink water often: Stay hydrated—even before you feel thirsty. Avoid alcohol and caffeine.

• Limit outdoor activities: Stay indoors during the hottest times of the day (11 a.m. – 4 p.m.).

• Use sun protection: Wear sunscreen (SPF 30 or higher), a hat, and light, loose clothing. Reapply sunscreen every 2–3 hours.

• Find shade or cooling spaces: Use an umbrella, visit a shady park, or head to a cooling centre.

• Cool down at home: Take a cool shower or bath. Use a fan with ice water nearby to make a refreshing breeze.

• Protect children and pets: Plan outdoor play for early morning or evening. Teach sun safety and ensure kids take breaks in shaded or cool areas. Never leave children or pets in vehicles, even briefly.

What are the signs of heat-related illnesses and how to treat them?

Knowing the signs of heat-related illnesses can save lives. Here's what to watch for and how to respond:

Heat cramps

• Symptoms: Painful muscle spasms, heavy sweating.

• Treatment: Rest in a cool place, gently massage muscles, and drink water. Stop if nausea occurs.

Heat exhaustion

• Symptoms: Cold, clammy skin, weakness, fainting, vomiting.

• Treatment: Move to a cool space, loosen clothes, apply wet cloths, and sip water. Seek help if vomiting continues.

Heat stroke (Emergency)

• Symptoms: High body temperature (41°C+), confusion, rapid pulse, or unconsciousness.

• Treatment: Call 911 immediately. While waiting, cool the person with lukewarm water and remove outer clothing. Do not give fluids.

What should I do next?

Learn about public weather warnings and visit these websites for more information:

• Health Canada: Keep Children Cool! Protect Your Child From Extreme Heat

• Health Canada: You’re Active in the Heat. You’re at Risk! Protect Yourself From Extreme Heat

• Health Canada: It’s Way Too Hot! Protect Yourself From Extreme Heat

• Ontario Ministry of Labour: Heat Stress

• Health Canada: UV Index and Sun Safety