Heat Warnings in Canada: What They Mean and How to Prepare
In the summer of 2025, the tiny village of Lytton, B.C., hit a staggering 42.1°C, becoming the hottest spot in Canada for the year. That kind of heat isn't just uncomfortable; it's a serious wake-up call. When Environment Canada issues a heat warning, they're not just telling you to expect a hot day. They're sending a critical alert that conditions are becoming dangerous.
So, what does that alert actually mean for you and your family? And more importantly, how can you prepare for it? Let's break down the facts and create your personal action plan.
What Exactly Is a Heat Warning?
Think of a heat warning as an official signal that the weather isn't just hot—it's dangerously hot.
It’s not about a single hot afternoon. Environment Canada issues a heat warning when the forecast shows a period of intense heat is coming, one that poses a real risk to your health. The biggest concern is sustained heat, especially when the nights don't cool down enough. This lack of a cool-down period is what puts a dangerous amount of stress on your body, preventing it from recovering. A warning gives you time to prepare for these risky conditions.
A Word You'll Hear: Humidex
When you see a heat warning, you'll often encounter a term called the Humidex.
What it is: The Humidex is a Canadian innovation that combines temperature and humidity into a single number. Think of it like the "feels like" temperature on your weather app, but specifically for sticky, humid heat.
Why it matters: High humidity is a problem because it stops your sweat from evaporating, which is your body’s natural air conditioner. A 30°C day can easily feel like 40°C when it's humid. A Humidex reading of 40 or more is a major red flag that you need to take it easy, as any strenuous activity becomes dangerous.
The Numbers Game: What Triggers a Warning in Your Province?
Here’s something most people don’t realize: the temperature that triggers a heat warning in Toronto is different from what triggers one in Yellowknife. The criteria are tailored to the local climate because what’s normal in one region can be an extreme event in another. A warning is typically issued when these conditions are expected to last for at least two days straight.
Here’s a detailed breakdown of the criteria across Canada:
Region | Daytime High Temperature | Nighttime Low Temperature |
British Columbia (South Coast) | ≥ 29°C | ≥ 16°C |
British Columbia (Interior) | ≥ 35°C | ≥ 18°C |
Alberta, Saskatchewan, Manitoba | ≥ 32°C | ≥ 16°C |
Ontario (Southern) | ≥ 31°C | ≥ 20°C |
Ontario (Northern) | ≥ 29°C | ≥ 18°C |
Quebec | ≥ 33°C | ≥ 20°C |
Atlantic Canada (NB, NS, PEI) | ≥ 30°C | ≥ 18°C |
Newfoundland | ≥ 28°C | ≥ 16°C |
Labrador | ≥ 25°C | ≥ 14°C |
The Territories (Yukon, NWT) | ≥ 28°C | ≥ 14°C |
Nunavut | ≥ 22°C | ≥ 12°C |
Note: In many parts of Ontario and Quebec, a warning can also be issued if the Humidex is expected to reach 40 or higher.
More Than Just Discomfort: The Health Risks
Extreme heat is sneaky. It doesn’t have the dramatic visuals of a tornado or a flood, but it is one of the deadliest types of weather events. When your body can't cool itself down properly, it can lead to serious and even fatal health problems.
It’s crucial to know the signs that your body is in trouble.
Heat Exhaustion vs. Heat Stroke: Know the Difference
Think of heat exhaustion as your body’s warning light flashing. Heat stroke is the engine failing. Knowing the difference can save a life.
Heat Exhaustion | Heat Stroke (Medical Emergency!) |
What it is: The body's response to an excessive loss of water and salt through sweating. | What it is: The body can no longer control its temperature. The sweating mechanism fails, and body temperature can rise to dangerous levels. |
Symptoms: | Symptoms: |
● Heavy sweating | ● High body temperature (above 39.4°C / 103°F) |
● Cool, pale, or clammy skin | ● Hot, red, dry, or damp skin |
● Fast, weak pulse | ● Fast, strong pulse |
● Nausea or vomiting | ● Headache |
● Muscle cramps | ● Dizziness, confusion, or loss of consciousness |
● Tiredness or weakness | ● Nausea |
What to do: Move to a cool place, loosen clothes, sip water, and apply cool, wet cloths. | What to do: Call 911 immediately. Move the person to a cooler place and use cool cloths or a cool bath to lower their temperature. Do not give them anything to drink. |
Who Needs Extra Care?
Everyone needs to be careful in the heat, but some people are more vulnerable. Be sure to check in on:
Seniors (especially those over 65)
Infants and young children
People with chronic health conditions like heart disease or diabetes
Anyone who works or exercises outdoors
Friends and neighbors who live alone
Your Simple Plan for Staying Safe in a Heatwave
You don’t need to do a lot to be prepared, but you do need a plan.
Before the Heat Arrives
A little prep work makes all the difference.
- Find Your Cool Zone: Figure out which room in your house is naturally the coolest (like the basement). That’s your go-to spot. Also, look up where your town’s public cooling centers are (libraries, community halls, etc.).
- Test Your Gear: If you have an air conditioner, turn it on to make sure it’s working. Get your fans out and give them a quick clean.
- Block the Sun: Blackout curtains or even just closing your blinds during the day can dramatically lower the temperature inside.
- Plan Easy Meals: Stock up on things that don’t require you to turn on the oven. Think salads, sandwiches, and fruit.
During the Heat Warning
When the heat is on, your only job is to stay cool and hydrated.
Drink More Water Than You Think You Need: Don't wait until you're thirsty. Keep a water bottle with you and sip on it all day.
Dress Light: Loose, light-colored clothing is your best friend.
Avoid Midday Sun: Do your errands or outdoor tasks in the early morning or late evening when it’s coolest.
Cool Off: A cool shower or bath works wonders. Even just soaking your feet in cool water can help.
Never, Ever Leave Kids or Pets in a Car: It takes only minutes for the inside of a car to reach deadly heat warning temperature.
The Overlooked Threat: Power Outages
Here’s the thing that can make a tough situation truly dangerous: the power goes out. Heatwaves put a huge strain on the electrical grid, and blackouts are common. Suddenly, your AC and fans are useless.
This is when having a backup plan isn't just a nice idea—it's essential.
A reliable portable power station can be a game-changer. For running bigger things like a fridge, a window AC unit, or multiple fans, an EcoFlow DELTA series unit provides serious power to keep your home’s essentials online. For smaller needs, like keeping a fan and some lights on, the grab-and-go EcoFlow RIVER series is perfect.
But what about your food? A power outage can spoil a fridge full of groceries in hours. A portable fridge like the EcoFlow GLACIER is an amazing tool. It not only keeps your food and medication safe, but it also has a built-in ice maker—a huge relief in extreme heat. You can power it for days with your DELTA or RIVER station.
Finally, don't forget your phone. It’s your link to emergency alerts and family. A small, fast-charging power bank from the EcoFlow RAPID series is perfect for keeping in a bag so your communication line is always open.
Stay Cool and Be Ready
A heat warning is a serious signal, but it doesn't have to be scary. With a little knowledge and a simple plan, you can handle whatever the summer throws at you. Prepare your home, know the signs of heat illness, check on your neighbors, and have a backup plan for the unexpected. Stay safe and stay cool out there.
Summer's heat is a force of nature, but how you respond is entirely within your control. A heat warning isn't a reason to be anxious; it's a signal to be prepared. By understanding the risks and having a simple plan, you can turn worry into action. It’s about more than just staying comfortable for a few days—it’s about building a resilient home and community that can handle whatever the weather throws its way.
Don't wait for the power to go out to think about your backup plan. Be ready for this summer and all the seasons to come.
Explore EcoFlow's emergency preparedness solutions and build your home's resilience today.
4 Frequently Asked Questions About Extreme Heat Survival
1. What is a "heat dome" and why is it so dangerous?
A heat dome is a weather phenomenon that acts like a lid on the atmosphere. A strong, high-pressure system traps hot air underneath it, pushing it back down to the ground and heating it even more as it compresses. This prevents cooler air from moving in and clouds from forming, leading to relentlessly sunny and dangerously hot conditions that can last for days or even weeks.
Unlike a typical heatwave that might last a day or two, a heat dome creates a prolonged period of extreme heat with no relief, which is what makes it so dangerous.
2. How can I keep my pets safe during an excessive heat warning?
Pets are just as vulnerable to heat as we are. So you should:
Always provide them with plenty of fresh, cool water, and make sure they have a shady spot to rest, whether inside or out.
Never shave a double-coated dog, as their fur actually helps insulate them from the heat.
Avoid walks on hot pavement, which can burn their paw pads—if it’s too hot for your hand, it’s too hot for their paws.
And, of course, never leave them in a parked car, where temperatures can become fatal in minutes.
3. Is it safe to use a portable gas generator during a heat-related power outage?
While gas generators can power your home, they come with significant safety risks. They must be operated outdoors, at least 20 feet away from any doors or windows, to prevent deadly carbon monoxide poisoning. They are also loud and require you to store flammable fuel, which can be a hazard in itself. For these reasons, many people now prefer portable power stations. They are silent, produce no emissions, and are safe to use indoors, allowing you to power essentials like fans or a small fridge right where you need them.
4. Besides my own home, how can I help my community prepare for extreme heat?
Community resilience is key during a heatwave. A simple but powerful action is to check on elderly neighbors or anyone living alone who might be more vulnerable. Share official information from public health agencies about cooling center locations and hours on social media or in community groups. If you have space in an air-conditioned car, you could offer a ride to a cooling center for someone who doesn't have transportation.
These small acts can make a huge difference and help ensure everyone stays safe.