Skip to main content

Extreme heat and humidity in southern Ontario all week


Sweltering temperatures have settled across southern Ontario and Environment Canada says the dangerously hot and humid weather will be sticking around for the rest of the week.

The agency issued a heat warning Monday for much of the province, from Windsor to Ottawa and from Sault Ste. Marie to Moosonee.

Environment Canada said daytime highs could range from 30 to 35 degrees Celsius, but with the humidity, it will feel closer to 40 or 45.

And we won’t get much relief overnight either.

The agency said it will drop to only 20 to 23 degrees Celsius at night, but will feel more like 26 to 30.

“As we get into the weekend we’ll start to see the daytime highs get cooler throughout the southwest,” added CTV News Kitchener Weather Specialist Will Aiello.

Under the heat dome

Dave Phillips, a senior climatologist with Environment Canada, says the province is experiencing a heat dome. That’s the term used to describe high-pressure areas where air sinks and is trapped, as if it’s been capped by a lid. Heat domes can last between five and seven days.

“The end of the heat dome is often the worst because you’re just not used to it,” he explained in an interview with CP24 on Monday. “The body can stand one day or two days.”

Anything longer than that could be challenging, he said.

Phillips added that this is the first but not the last heat wave of the summer.

Signs of heat illness

Heat illness is a serious concern when the mercury rises, especially in older adults, infants, young children, pregnant people, those with physical or mental illnesses, people with mobility issues, those who work outside and the homeless community.

Symptoms of heat illness include:

  • Swelling
  • Rash
  • Cramps
  • Fainting
  • Heat exhaustion
  • Heat stroke

Keeping cool

Brandie Bevis, a health promotion and research analyst with Region of Waterloo Public Health, said our bodies are not acclimatized to the warmer temperatures since it’s still early in the season for a heat wave.

“It’s really important to take breaks from the heat as much as you can. Get into a cool place, ideally a place with air conditioning, and really focus on staying hydrated and specifically hydrated with water,” she advised.

It’s also important to keep your home cool.

“If you have air conditioning, this is the week to use it,” Bevis said. “If you don’t have air conditioning, you’re going to want to close your blinds and keep that sunlight out of your home during the hottest parts of the day. Maybe not using heat sources to cook your food during this week – it’s a cold sandwiches kind of week.”

Heat-related illnesses are a concern because they can lead to heat exhaustion and, potentially, heat stroke.

“With heat exhaustion, you might feel very confused or dizzy and lightheaded. You might get a headache. You might find that you’re urinating less frequently or that maybe it’s a little more yellow. That’s really an indicator that you’re going to want to drink lots of water. When this happens, it can really have an impact on your body and it can lead to heat stroke,” Bevis explained. “A heat stroke is a medical emergency. That’s when your core body temperature reacha 40 degrees Celsius and that [means] a trip to the hospital.”

For those with air conditioning units, experts say it’s important to check the system before cranking it up full blast.

“You want to make sure your air filters have been changed – that’s very important,” Robert Benner, a service technician with Able Air KW, explained. “Make sure the batteries on the thermostat have been changed, and you want to make sure there’s nothing on top of the air conditioner, or around it, and if you’re unsure of all of this then book a tune up.”

Beating the heat

The key to avoiding heat illness is to plan ahead.

The Region of Waterloo suggests:

  • Know the weather forecast before going outside
  • Modify your plans according to the weather
  • Drink plenty of cool liquids, especially water, before you feel thirsty
  • Avoid drinks that are high in sugar, caffeine or alcohol
  • Wear loose-fitting, light-coloured clothing made of breathable fabric
  • Seek shade
  • Avoid sun exposure if you can
  • Take breaks as needed
  • Avoid using your oven
  • Take a cool shower or bath
  • Take a break from the heat by spending a few hours in a cool place

Cooling centres

The best way to get relief from the heat and humidity is to take a break in a designated cooling centre.

The Region of Waterloo has them listed on their website. They include libraries, community centres, museums and regional offices.

The map also includes a list of public swimming pools and splash pads.

Protecting your pets

Humans aren’t the only ones who need to avoid the heat this week – animals are also at risk.

Stacy Murphy, a registered veterinary technician at the Humane Society of Kitchener-Waterloo & Stratford Perth, said people need to look out for animals who have been left unattended in hot vehicles.

“Any time we’re having weather where it’s quite hot – or even remotely hot – you should be careful,” she explained. “Animals can overheat while in cars, even if the windows are down, even if it’s in a shaded area. When it’s hot like this, anything really above 16 degrees, you should just leave the animal at home.”

On hot days, Murphy suggests keeping animals off of the pavement as much as possible.

“Taking them for walks on grass so their paws don’t get too heated, keeping walks shorter, walking in the morning or later in the evening when it’s a little bit cooler,” she recommended.

It’s also important to know the signs of an overheated pet.

Murphy said they may pant excessively, become lethargic, and their tongue could appear red or hang out of their mouth.

“If your animal does become overheated, it’s important not to make them too cold too fast,” she added. “If they’re overheated, getting a cool blanket or cool towel that’s wet just to cool them off is a good idea. But definitely avoid ice because we don’t want to make them too cold too quick.”

The Waterloo Regional Police Service is also asking drivers to keep their pets at home.

They’ve already received 10 calls about pets left alone in hot vehicles since the start of June.

Anyone concerned about the wellbeing of animal is asked to call 911.

- With files from CTV News Toronto Top Stories

Ben Affleck and Jennifer Lopez publicly list their house for sale

Ben Affleck and Jennifer Lopez have added a tiny bit of fuel to the fire surrounding their marriage. Amid speculation that the pair are struggling in their relationship after marrying about two years ago, the couple has listed their 12-bedroom, 24-bathroom California home for sale.

Stay Connected