Extreme Heat and Humidity

Heat illness

Symptoms of heat illness:

• Heat edema (swelling of hands, feet, and ankles).
• Dizziness or fainting.
• Nausea or vomiting.
• Headache.
• Fast breathing and heartbeat.
• Extreme thirst.
• Less urination and very dark yellow urine.
• Changes in behaviour (sleepiness or temper tantrums in children)

Common heat illnesses:

• Heat edema (swelling of hands, feet, and ankles).
• Heat rash.
• Heat cramps.
• Heat fainting.
• Heat exhaustion.
• Heat stroke.

Heat stroke

Heat stroke is a medical emergency. If you or someone else is having a heat stroke, call 911.

Heat stroke symptoms:

• High body temperature.
• Unconscious.
• Confused.
• Not sweating.
• Signs of heat illness.

While waiting for medical help, you should:

• Move yourself or the person to a cool place, if possible.
• Place cold water on skin or clothing.
• Fan yourself or the person.

Your body cools down by sweating. Your sweat cools your body as it evaporates. The weather affects how you stay cool. If it's windy, sweat evaporates faster, which helps to cool you faster. High humidity slows your body's ability to cool down.

If you are feeling any of these symptoms in hot weather, you should:

• Move to a cool place such as an air-conditioned room or under some shade.
• Drink sips of water or other liquids.
• Cool off by taking a cold shower or using a fan.

If the above cooling tips do not make you feel better, seek emergency help or call 911.

Extreme heat affects everyone.

You are at greater risk if you:

• Are a senior.
• Are an infant or child.
• Have an existing illness (difficulty breathing, diabetes, heart condition, mental illness).
• Work outside.
• Exercise outside.
• Are homeless.
• Live by yourself and have problems with movement.
• Are on medication that affects how you deal with heat.

• Never leave people or pets inside a parked car.
• Outside temperatures of 23°C /73°F can become dangerously hot inside the car with temperatures becoming higher than 50°C/122°F inside the car, which can lead to serious illness and death.

Anyone seeing a child left unattended in a hot vehicle at anytime should call 911 immediately.

You can protect yourself and try to prevent heat and humidity related illnesses by:

• Checking weather forecasts for hot weather and Environment Canada for heat warnings.
• Checking if your air conditioner works before hot weather starts.
• Making your home cooler by planting trees for more shade.
• If you have no air conditioner, find a place to cool off during hot weather.
• If you take medication, check with your doctor to find out how extreme heat may affect you.
• If you have no air conditioning or have a medical issue, then have family, friends, and neighbours visit on hot days to check if you are okay.
• Staying hydrated by drinking lots of fluids, especially water.
• Wearing loose fitting clothing while outside.
• Covering exposed skin when out in the sun.
• Wearing a wide-brimmed hat when in the sun.
• Wear sunglasses with UVA and UVB protection for your eyes.
• Using an umbrella for shade.
• Using a sunscreen with SPF30 or higher.
• As a last resort, seek shade as it can reduce the temperature outside by 5°C.
• Schedule your outdoor time during cooler times of day (morning and night).
• Check the Air Quality Health Index as air pollution can be higher during very hot days.
• Reschedule your plans for a cooler day or choose a location with shade or air conditioning near you.

There are ways to keep your home cool even without an air conditioner:

• Try cooking outside instead of using the stove or oven.
• Close curtains or blinds during the day.
• If the night is cooler, open windows to cool home.

Use your air conditioner. If you are using a window air conditioner, cool the one room you will use for a heat break.

If your home is extremely hot:

• Take cool showers.
• Use a fan.
• Leave home and visit a place with shade, a pool, or an air conditioned space such as malls, libraries or stores.

• Town of Ajax
• Municipality of Clarington
• City of Oshawa
• City of Pickering
• Township of Scugog
• Town of Whitby

Subscribe to notification of heat events

Durham Region Health Department gives local municipalities and community partners early notification of extreme heat events as they have services for those who are more vulnerable to heat.  

If your organization provides services for heat vulnerable people, you may subscribe to heatalert@durham.ca for the early notification emails.

Heat warning gauge

These images tell you what the current heat warning status is for Durham Region.

Visit Environment and Climate Change Canada's website for more weather information.