Extreme Heat

High temperatures are mostly seen during the summer but can also happen in the spring and fall. Waterloo Region will likely see more days of high temperatures each year. This is a result of climate change.

Extreme heat can affect the health of everyone and can be life-threatening. It is important to protect yourself and others from extreme heat. Cooling spaces are available throughout Waterloo region for relief from extreme temperatures.

Heat related illness

Heat illness includes heat stroke and heat exhaustion. Heat can also cause muscle cramps, swelling of the hands, feet, and ankles as well as heat rash.

Watch for the early signs of heat exhaustion in yourself and others. Signs may include headache, nausea, dizziness, thirst, dark urine and feeling very tired. If you see these signs, stop your activity and drink water.

Heat stroke is a medical emergency! Call 911 if you, or someone around you, shows signs of heat stroke. Signs of heat stroke are red and hot skin, dizziness, nausea, confusion and change in a person’s normal mental state.

Who is more at risk for heat-related illness?

Older adults
Infants and young children
People with chronic illnesses (like breathing problems, mental illness and heart problems)
People who are unable to keep their living space cool
People who work in the heat (indoors or outdoors)
People who exercise in the heat (indoors or outdoors)
People who are experiencing homelessness
People with low incomes

Protect yourself and others from the heat

Check on people who are more at risk several times a day by calling or visiting them.
Plan outdoor activities during the coolest parts of the day.
Limit direct exposure to the sun.
Wear lightweight, light-coloured, loose-fitting clothing and a wide-brimmed hat.
Drink water often and before you feel thirsty. Make sure to give pets water as well. Avoid sugary or alcoholic drinks which can cause dehydration.
Take cool showers or baths to cool your body down. Use cool wet cloths or icepacks on your body, focussing on the neck, armpits and groin.
Never leave people, especially children, or pets inside a parked vehicle.
Seek places that have air conditioning.
Visit a Cooling Space. These are air conditioned spaces and welcome anyone inside during regular business hours.

Make indoor temperatures safe and comfortable

During heat events, indoor temperatures above 26°C (79°F) can increase health risks, especially for vulnerable individuals. Temperatures above 31°C (88°F) are dangerous for everyone.

In your home:

Turn on air conditioning, use a fan, or move to a cooler area of your home.
Close window blinds or shades.

When there is no air conditioning:

Open windows and doors to the outside and use fans to draw cooler air into the home
Move to a cooler environment such as:
- Your basement
- Outdoors (consider sleeping outdoors if it is safe to do)
- A gathering space in your building with air conditioning
- Stay with family or a friend with air conditioning
- Visit a Cooling Space, shopping centre or shaded park

Prepare for the heat season

Prepare your home

It is important to assess if you can safely stay in your home during high heat events that may last for days. It is dangerous if you are exposed to continued temperatures over 31°C (88°F) and you are at higher risk for heat-related issues

Three steps to cost-effective home, condo or apartment heat protection (Intact Centre on Climate Adaptation)

Prepare for heat event emergencies

A public health emergency can happen because extreme heat can cause many deaths. In 2021 British Columbia had over 600 heat-related deaths within a few weeks. Many of these people lived alone without air conditioning. Extreme heat can also cause other emergencies such as power outages. It is important to be ready for an emergency by preparing an emergency kit.

Visit Alert Waterloo Region for more information on emergency preparedness.

Protect yourself and others from the sun

Too much sun exposure can increase the risk of skin cancer and eye damage later in life. Children need extra protection because sun exposure during childhood can affect their long-term health. This is especially important in places where children gather or play.

If you are spending time in the sun, especially when the UV Index is 3 or higher, protect your skin as much as possible.

Seek shade or bring your own shade (e.g. an umbrella). Shade helps protect you from ultraviolet (UV) radiation, provides relief from the sun’s heat, and can help reduce the risk of overheating.

For anyone over six months old, use sunscreen on all exposed skin that is at least SPF 30, labelled broad-spectrum and water-resistant. Reapply sunscreen and SPF-containing lip balm, especially after swimming or sweating.

Keep babies under one year out of direct sunlight to prevent skin damage and dehydration. Never let them play or sleep in the sun. Sunscreen is not recommended for babies under six months old.

Wear sunglasses or prescription eyeglasses with UVA/UVB protective lenses year-round, even when it is cloudy, particularly around sand, water, and even snow.

Wear a wide-brimmed hat and loose clothing that covers as much skin as possible.

Between April and September, plan outdoor activities for before 11 a.m. or after 3 p.m.

Be careful around surfaces exposed to direct sun, like playground equipment, benches, pavement, and sports equipment. They can get hot enough to burn skin. Check them before touching or using them, especially for children. Choose shaded areas when you can.

For more tips on sun protection, visit Health Canada's sun safety web page and the Canadian Cancer Society Be Sun Safe web page.

Heat warnings

Environment and Climate Change Canada issues heat warnings when one or both of the following conditions are met:

Two days in a row where the temperature is forecast to be 31° C or higher during the day and 20° C or higher overnight.
Two days in a row where the humidex is forecast to be over 40° C.

The humidex is a measure that combines the heat and humidity in the air which describes how hot it feels to the average person. The higher the humidex means the hotter it feels for people.

Weather alerts are issued as warnings with different colour codes (yellow, orange or red) based on possible risks.The message is simple: know the colour, know the risk. Visit Environment and Climate Change Canada for more information on colour-coded weather alerts.

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