UPDATED HEAT WARNING
July 26, 2023 – A forecast calling for three consecutive days of hot and hazy summer weather has led forecasters at Environment Canada to issue a Heat Warning for London and Middlesex County. The Middlesex-London Health Unit is using this as an opportunity to remind the public to take steps to stay cool and to keep hydrated as summer temperatures climb. The Heat Warning is expected to come into effect on Wednesday, July 26th and to be lifted overnight on Friday, July 28th, when the overnight low is expected to fall to 12°C. The current Environment Canada forecast calls for a three-day temperature spike with tomorrow’s daytime high expected to reach 30ºC with a humidex value of 37; similar conditions are expected for Thursday, while Friday’s high is expected to reach 32ºC.
Each summer, London and Middlesex County experience periods of extreme heat. The Middlesex-London Health Unit issues the following when one or more of the criteria are met:
- Environment Canada issues a forecast indicating a daily maximum temperature of 31oC or higher with a minimum temperature of 20oC or higher for two consecutive days, or
- Environment Canada issues a forecast indicating a daily Humidex of 40 or higher for a duration of two consecutive days.
Extended Heat Warning
- Environment Canada issues a forecast indicating a daily maximum temperature of 31oC or higher with a minimum temperature of 20oC or higher for duration of three consecutive days or longer, or
- Environment Canada issues a forecast indicating daily Humidex of 40 or higher for a duration of three consecutive days or longer.
Are You at Risk?
During a heat wave, everyone is at risk, but some groups are more vulnerable than others. They include:
- Infants (under 1 year of age).
- People 65 years of age or older.
- People with chronic medical conditions (heart disease, respiratory conditions, diabetes, etc.).
- People on certain types of medications (for high blood pressure, depression, insomnia, etc.).
- People experiencing homeless.
- People with limited mobility.
- People with mental impairment.
- People who exercise vigorously outdoors (play sports, cyclists, gardeners).
- Outdoor workers (depending upon length or time and exertion levels).
- People who work in places where heat is emitted through industrial processes (e.g., foundries, bakeries, dry cleaners).
Please see Ontario’s website for further advice about heat stress.
Health Risks of Extreme Heat: Know When to Get Help
Seek help if you experience any of the following symptoms of heat illness:
- Heat cramps
Symptoms/signs include painful muscular cramps, usually in the legs or abdomen.
- Heat exhaustion
Symptoms/signs include heavy sweating, weakness, dizziness, nausea, vomiting, fainting.
- Heat stroke
Symptoms/signs include headache, dizziness, confusion or other altered mental state, fainting. Skin may be hot and dry, or the individual may be sweating due to high body temperature. This is a potentially life-threatening emergency – call 911 immediately.
Things You Can Do to Protect Yourself
- Check the Government of Canada’s Weather Information website.
- Check the Ministry of the Environment and Climate Change’s Air Quality in Ontario website for information regarding air quality and the Air Quality Health Index.
- Drink plenty of water and natural juices throughout the day, even if you don’t feel very thirsty. Remember to take sips often and to not guzzle your drink.
- Avoid drinking alcoholic beverages, or beverages that contain caffeine like coffee, tea and cola.
- Whenever possible, avoid spending extended periods of time outside during extreme heat. Instead try to spend time in air conditioned rooms. During prolonged periods of extreme heat the City of London designates Cooling Centres, where you can go to cool off. If you have to go outside, try to stay in the shade as much as possible. Plan any necessary outdoor activities in the early morning or evening, when temperatures are lower.
- Wear a wide-brimmed hat 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.
- Take a cool bath or shower periodically or cool down with cool, wet towels.
- Wear loose fitting, light clothing.
- Avoid eating heavy meals and using your oven.
- Avoid intense or moderately intense physical activity.
- Never leave a child or pet in a parked car or sleeping outside in direct sunlight.
- Use fans to draw in cool air at night, but do not rely on a fan as a primary cooling device during extended periods of excessive heat.
- Consult your doctor or pharmacist regarding the side effects of your medications which could be triggered by extreme heat.
- Reduce the use of personal vehicles, stop unnecessary idling; avoid using oil-based paints and glues, pesticides and gas-powered small engines (lawn mowers, weed whackers, etc.).
What can I do to help someone who is suffering from a heat illness?
Friends and relatives can help someone with heat illness by doing the following:
- Call for help. Call 911, consult a healthcare provider or call Telehealth Ontario (1-866-797-0000 or TTY at 1-877-797-0007).
- Move the person to a cooler location.
- Remove excess clothing from the person.
- Cool the person with lukewarm water, by sponging or bathing.
- Give the person sips of cool water if they are not nauseated or vomiting. Do not give ice cold water.