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Preparing for Heat Events


Learn about heat illnesses and how to take precautions and prevent health issues in extreme heat.

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Halton Region will issue Extended Heat Warnings (heat events longer than 3 days), or Special Air Quality Statements related to forest fires or other emergency events on our newsroom.

Heat events

As the climate changes, heat events are expected to become more frequent, longer and hotter in Halton Region and other parts of Ontario.

Heat events can affect anyone's health. Extreme heat can cause a high risk of severe illness for some people if they do not have access to a cool indoor environment. Heat can rise indoors when the outdoor temperatures are climbing every day, and the situation can become dangerous.

Indoor heat can be dangerous, especially if the temperatures stay over 31°C for long periods. If you are at risk and it gets very hot in your home during extreme heat events, plan to go somewhere cooler if possible.

Are there cooling centres in Halton?

Cooling Centres and Recreation Water Facilities

For information on hours and locations of cooling centres, pools and splash pads visit your local municipality’s websites below:

What is a heat warning/extended heat warning and when is it issued?

Heat Warning

Environment and Climate Change Canada will issue a Heat Warning when forecast temperatures are expected to be at least 31°C and overnight temperatures are above 20°C for 2 days or the humidex is at least 40 for 2 days.

Extended Heat Warning

Halton’s Medical Officer of Health will issue an Extended Heat Warning when forecast temperatures are expected to be at least 31°C and overnight temperatures are above 20°C for at least 3 days or humidex is at least 40 for at least 3 days.

What is humidex?

Humidex describes how hot, humid weather feels to the average person. This measurement is calculated using temperature and humidity readings.

Who is at greatest risk from extreme heat?

Extreme heat and humidity are dangerous to everyone; however some people are at greater risk including:

  • Older adults (over the age of 65)
  • People who live alone or who are socially isolated
  • People with mental illnesses
  • People with chronic health conditions such as diabetes, heart disease or respiratory disease
  • People who have a disability
  • People with limited mobility
  • People with cognitive impairment
  • People with substance use disorders
  • People who do not have access to adequate housing
  • People who work in hot environments (such as outside or in kitchens)
  • People who exercise in the heat
  • Pregnant people
  • Infants and young children

Preparing for hot weather

Prepare your space
  • Ensure your air conditioner works if you have one in your home. The Ontario Energy Board provides support for electricity bills for lower-income households. More information on the program and eligibility (external link).
  • Install awnings, shutters, blinds, or curtains over your windows to keep the sun out during the day.
  • Get a digital room thermometer to know when your home is getting too hot.
Your friends and family

Think of people you know who may be more susceptible to heat and develop a buddy system.

Your Health
  • If you take regular medications, drugs, or have a health condition, ask your doctor or pharmacist whether it increases your health risk in the heat and follow their recommendations.
  • Know the signs and symptoms of heat-related illness so you can identify problems early on. Severe headache, confusion, unsteadiness, loss of thirst, nausea/vomiting, and dark urine or no urine are signs of dangerous heat-related illness.

During heat events

Keep your home cooler by:

  • Making meals that don't need to be cooked in an oven.
  • Shutting windows and closing shutters, curtains, or blinds in the morning to keep cooler air in and to keep the sun out.
  • Opening windows and doors at night when the outdoor temperature goes down.

Find cooler spaces in our community:

  • If you do not have air conditioning, spend time in cooler indoor spaces in the community like shopping centres or libraries.
  • Seek cooler, breezier areas when outdoors, such as large parks with water features and lots of trees.

Think of people you know who may be more susceptible to heat and check in with them often, especially in the evening when indoor temperatures are highest. If you cannot check in-person, ask them to tell you what it says on their thermostat or indoor thermometer.

Encourage those who may not know they are at higher risk to take cool baths, sleep in the coolest room, or stay with friends.

If your home is cooler, invite those who are at highest risk to stay with you.

Never leave children, dependent adults, or pets alone in a parked car, leaving windows open will not help.

Follow these tips to help you manage your health during a heat event:

  • Drink lots of water, even if you do not feel thirsty, especially during warm nights. Pay attention to the amount and colour of your urine. Dark yellow urine is a sign of dangerous dehydration.
  • Protect yourself from the sun and stay cooler by:
    • staying in the shade;
    • avoiding direct sun mid-day;
    • wearing a hat and protective clothing;
    • using sunscreen with Sun Protection Factor (SPF) of 30 or higher;
    • and wearing UV-protective eyewear.
  • Lower your activity level and avoid intense activity. If you need to do errands, do them when it is cooler outside, early or late in the day.
  • Watch out for severe headache, confusion, unsteadiness, loss of thirst, nausea/vomiting—they are signs of dangerous heat-related illness (heat stroke).
  • If you are experiencing heat-related illness, take immediate action to cool down and call for help if needed. Dangerous heat-related illness (heat stroke) is a medical emergency.
  • Cool down your body by:
    • wearing a damp shawl or shirt;
    • sitting in a cool or tepid bath to draw heat from the body into the water;
    • taking a cool shower;
    • using a damp sheet at night;
    • putting an ice tray in front of a fan; or
    • using a personal mister or spray bottle.
  • Sleep in the coolest room of the house, even if that is not your bedroom.

Children are not always able to recognize how heat events can affect them. Follow these tips to protect children during heat events:

  • Ensure they stay hydrated with plenty of water.
  • Apply and reapply sunscreen throughout the day.
  • Ensure they are wearing hats, sunglasses and light-weight clothing in breathable materials.
  • Avoid being outside during the hottest part of the day.
  • Seek cool places such as community centres, libraries, splash pads, waterparks or pools.

Pregnant people can be more vulnerable to heat exhaustion or heat stroke, particularly if they have other health concerns. Drink plenty of water, follow the tips on this page to stay cool, and avoid increased physical activity during hot weather.

Know the signs and symptoms of heat-related illness

Symptoms of severe heat-related illness

Severe heat illness and heat stroke are medical emergencies. Call 9-1-1 if you are caring for someone with signs or symptoms of severe heat-related illness, including:

  • Severe nausea and vomiting
  • Fainting or loss of consciousness
  • Confusion or disorientation
  • Difficulty speaking
  • Movement and coordination problems
  • Lethargic
  • Not sweating
  • Hot, flushed skin or very pale skin
  • Not urinating or very little urinating
  • Rapid breathing and faint, rapid heart rate

While waiting for help to arrive, cool the person by:

  • moving them to a cool place, if you can;
  • removing excess clothing.
  • applying cold water, wet towels or ice packs around the body, especially the neck, armpits, and groin.

Symptoms of mild to moderate heat-related illness

Symptoms of mild to moderate heat-related illness include:

  • Headache
  • Nausea
  • Weakness
  • Irritability
  • Light-headed or dizziness
  • Disorientation
  • Thirst or dry mouth
  • Difficulty swallowing
  • Fatigue, malaise
  • Heat rash, heat edema or heat cramps
  • Decreased urine output
  • Increased heart rate
  • Skin feels very warm and sweat

Contact a healthcare provider if you are unsure if you are experiencing mild to moderate heat-related illness. Mild to moderate heat-related illness can quickly become severe—if symptoms get worse, call 911.