What Is the Difference Between a Heat Warning and a Heat Advisory?

What Is the Difference Between a Heat Warning and a Heat Advisory?

In Canada, extreme heat can be dangerous. This is especially true to vulnerable people. Thus, understanding the difference between a heat warning and a heat advisory is crucial. It will help you stay safe from hot weather. Environment Canada uses both terms to alert the public about hazardous heat conditions but vary in terms of purpose and threshold. This article will explain each term, the criteria, and how to protect oneself from the deadly heat wave.

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What Is a Heat Warning in Canada?

A heat warning is issued in Canada by Environment Canada when temperatures or humidex values are expected to reach a level of risk to one's health on two or more consecutive days. The specific warning criteria are region-based because the climate in Canada is very diverse. For example, in Nova Scotia, a heat warning comes when the maximum temperature over the day is forecast to be 29°C or higher, and the temperature does not go lower than 16°C over two days continuously. In southwestern British Columbia, the threshold values are much higher—in the vicinity of 33°C by day and with minimums greater than 17°C over two days.

It is issued to the general public to take preventive measures from possible heat-induced illnesses, such as exhaustion or stroke. During such periods, the most vulnerable groups are usually older people, younger population, people suffering from chronic ailments, and those unable to access air conditioning. The system of heat warnings developed by Environment Canada aims to provide timely information that will help ensure personal safety and limit health risks related to aggravating heat.

What Is a Heat Advisory?

Environment Canada also issues a Heat Advisory, although generally for conditions that are not considered as serious as a Heat Warning. In general, heat advisories are often issued when daytime temperatures are expected to be high but not as extreme, and, therefore, the heat is not supposed to last as long. The criteria for a heat advisory can also vary by region, reflecting local climate and health impacts.

It is an alert to the public that preparations need to be made for hot conditions, though less severe than a heat warning. It includes the idea of hydration, not undertaking serious activities during the hottest hours of the day, and staying cool in apparently more incredible places. Like a heat warning, advisories are most important to care about vulnerable populations.

What Is the Difference Between a Heat Warning and a Heat Advisory?

This lies in two primary aspects. In Canada, the distinction between a heat warning and a heat advisory lies in their level of severity and length, as forecasted under conditions of heat. A heat warning is released when temperatures or the humidex value are expected to reach unusual heights with a potential danger to health for at least two full days. It indicates a higher level of urgency and calls for immediate actions to save health, primarily for vulnerable groups.

On the other hand, a heat advisory is issued for conditions that are still hot and potentially hazardous but do not meet the higher thresholds required for a heat warning. Heat advisories usually last for shorter periods or when the forecasted temperatures are not that extreme. While advisories still urge caution and preventative measures, they signal a lower level of immediate risk than heat warnings.

However, there are also regional thresholds for both health warnings and advisories in the provinces and territories that take into account local climate differences. In Manitoba, for example, heat warnings are issued based on specific daytime high and nighttime low temperatures, as well as humidex values. However, they vary across the northern and southern parts of the province. Such a threshold is determined based on historical temperature and humidity level data with an association of adverse health effects.

The communication strategies for these two forms of warnings also differ slightly. Heat warnings are typically issued to cause broader, often local public health responses that include opening cooling centers and extending the hours of public cooling facilities. In contrast, in their wake, heat advisories might provoke a mere remembering of people to stay calm and hydrated. Both have as their aim to reduce morbidity and mortality from excessive heat in delivering information on risks to action.

What Causes Extreme Heat?

Most commonly, high-pressure systems trap warm air within a region for an extended period, bringing about extreme heat events in Canada. These are also called heat domes, and they usher in sweltering periods of hot weather, such as those experienced during the summer months. In addition, climate change is fostering the rising frequency and intensity of extreme heat events. With the global temperature rising, it's raising the risk of heat waves across Canada.

Some geographic factors are essential in experiencing extreme heat. For example, cities tend to have built-in excess hotness from the urban heat island effect: buildings, roads, and other infrastructure absorb and hold onto heat. These make the cities remarkably warmer when compared to similar surrounding rural areas, hence exacerbating the effect of heat waves on urban dwellers.

Another one is humidity, which can make temperatures feel way hotter than they are. Humidex in Canada combines both temperature and humidity to inform how hot or muggy the weather reportedly feels to the average person. Extremely high humid levels are not good. They break the ability of the body to cool down through perspiration. Also, they may lead to heat-related illnesses.

How to Survive a Heat Wave?

Adhering to several measures, in turn, can protect you from the effects of heat in Canada to keep safe against the heat wave. Some of the ways to prevent the adverse effects of a heat wave are: 

  • Hydrate: Make an effort to keep yourself drinking at least a little sufficient water per day. Do this even if you don't feel thirsty. Stay away from alcohol and other meals/drinks that can cause the body to lose water.
  • Keep Cool: Everyone should minimize their exposure to heat; either go to an air-conditioned residence or into shades. Look out for thermally controlled sites, e.g., in shopping pools, libraries, or community centers.
  • Limit Outdoor Activities: Exercise during early morning hours. Also, do not engage in any rigorous activities during the day between 10 am and 4 pm.
  • Dress Right: Wear comfortable, light-colored, and breathable attire to easily regulate body temperature. Do not leave your home without a broad-brim hat, and use sunblock with a factor of 30 and above.
  • Look out for the vulnerable: Follow up with families, friends, and neighbors among the elderly, children, and colleagues with a few illnesses. 
  • Be Prepared for Power Outage: Conditions of these sorts can lead to a surge in electricity consumption.  In fact, at worst, they may even cause blackouts. Another important thing is to ensure that there are emergency kits at home. Check that they're containing stuff like water, food, flashlights, and batteries, among others. 
  • Cooling Methods: Consider taking cold showers and baths. Also, apply wet towels and ice packs to cool down the body. Fans can also be advantageous, but it is essential to use them with other cooling techniques because when used alone, they do not aid in reducing the body temperature in high temperatures.

Emergency Home Battery Backup Recommendations

During periods of extreme heat, it's common for blackouts to occur, leaving you literally sweltering without air conditioning and other critical electrical services. An emergency home battery backup system can come as a lifesaver during such extreme heat situations. Here are two recommended options:

BLUETTI AC300 + 1*B300 Backup

This one is a reliable and efficient home battery backup. With a total capacity of 3,072 Wh, this product can support your main appliances and electronic gadgets in case of a power outage. The modular design also allows for easy capacity expansion in the future, should the need arise. Besides, this system has multiple output possibilities, such as AC outlets, USB ports, and even a 12V carport. It is also designed to support input from a solar panel, thus recharging its battery from solar energy, which would primarily be very helpful in outages of longer durations.


The unit is possibly one of those highest-capacity power stations that can support the house with backups. Featuring a vast 5,120Wh capacity and 3,000W continuous output, probably all the necessary appliances in an average household are covered. This includes refrigerators, air conditioners, and medical equipment. The system has its built-in inverter, and both AC and solar charging are supported. EP500Pro also comes with advanced features such as an LCD touchscreen to monitor performance and a robust mobile app for remote control and management. With a high capacity and comprehensive features, it is an ideal solution for emergency preparedness.

Final Thoughts

Sufficient knowledge is required to tell the difference between a heat warning and a heat advisory to be safe from any kind of extreme heat event in Canada. The purpose of both alerts is to let those at risk know that dangerous heating conditions are present. Only the severity of the two alerts and their corresponding recommended action differ. With appropriate steps taken and an emergency plan developed, you can save yourself and your loved ones from the dangers of extreme heat. But invest in a home battery backup system to ensure continued power supply during these critical times. Also, always keep yourself informed of the heat conditions that exist around your location.

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