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Heat Warning Issued for the Leeds, Grenville, Lanark (LGL) Region

July 5, 2023

It’s hot outside and the extreme heat is expected to last into Friday which has resulted in Environment Canada issuing a heat warning. While many welcome the warmer weather, the Health Unit is sending a reminder that high temperatures may impact your health. Heat warnings are issued when:

  • Daytime temperature of 31°C or higher and nighttime temperature not cooler than 20°C lasts for at least two days, or;
  • Humidex of 40°C for at least two days are expected.

Becoming overheated can cause dehydration, heat exhaustion, heat stroke and, in some cases, death. Even short periods of exposure to high temperatures can cause health problems. If you experience the following symptoms after exposure to extreme heat, seek medical attention immediately:

  • Nausea, dizziness, blurred vision
  • Difficulty or rapid breathing
  • Severe headache or confusion
  • Convulsion
  • Fever

Everyone is at risk, however, the following people are in greater danger of being affected:

  • Elderly;
  • People with chronic illness or who take certain medications;
  • Infants and preschool children;
  • People who have challenges with housing and shelter;
  • People who participate in physical activity or are involved in strenuous outdoor work for prolonged periods.

During a Heat Warning, the public is strongly encouraged to check on a neighbour or a friend who may have a greater risk of suffering negative health consequences from the heat and humidity. Use this guide to check on friends and family.  

Dr. Linna Li, Medical Officer of Health for the Leeds, Grenville and Lanark District Health Unit (LGLDHU), advises to keep cool and hydrated when it is hot outside and to take the following precautions:

  • Do not leave children, adults or pets in parked cars or sleeping outside in direct sunlight.
  • Consult your doctor or pharmacist regarding the side effects of your medications.
  • Drink plenty of water throughout the day, even if you don’t feel very thirsty. Remember to take sips often and not to guzzle your drink. Learn more about hydration at
  • Eat foods that have high water content such as watermelon, grapes and oranges.
  • Limit caffeinated beverages such as coffee and cola.
  • Avoid going out in the blazing sun or heat. If you must go outside, stay in the shade as much as possible.
  • Take a cool bath or shower periodically or cool down with cool, wet towels.
  • Whenever possible go to an air-conditioned room or building.
  • Wear loose fitting, light clothing and a wide-brimmed hat when outdoors.
  • Keep window shades or drapes drawn and blinds closed on the sunny side of your home.
  • Keep electric lights off or turned down low.
  • Visit a local splash pad, wading pool, or cooling centre.
  • If you can, eat a variety of foods that can be prepared safely without using the oven.
  • Don’t skip meals. Instead, eat smaller amounts more often. Use Canada’s New Food Guide. Check out the snacks on this page.
  • Use fans to draw cool air at night, but do not rely on a fan as a main cooling device during long periods of high heat and humidity.
  • Reduce the use of personal vehicles, stop unnecessary idling; avoid using oil-based paints and glues, pesticides and gas-powered small engines.

For more information on how to protect your health during extreme heat, visit our Exposure to Hot/Cold Temperatures page. For specific heat-related health questions call 1-800-660-5853 or 613-345-5685. You can also connect with us on FacebookTwitter @LGLHealthUnit or Instagram @lglhealthunit.z for important public health updates.


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