As Canada endures an intense heat wave, experts are raising alarms about the potential for increased power outages and malfunctioning air conditioning systems. A report published by Environment and Climate Change Canada (ECCC) in February 2025 highlights that “prolonged periods of extreme heat events can strain the power grid as the demand for air conditioning and fan use increases,” leading to localised outages. The looming threat of cascading failures—where a single grid malfunction triggers widespread outages—has been underscored by civil engineering professor Jeff Siegel from the University of Toronto.
Understanding the Impact of Extreme Heat
Ontario and Quebec are currently under orange alert heat warnings, which elevate the risk of power disruptions throughout the summer months. Professor Siegel notes that the frequency of extreme heat events—characterised by sustained high temperatures over multiple days without respite—has risen significantly. “We are seeing increased frequency of these yellow, orange, and red extreme heat events, and we’re noticing a corresponding spike in grid issues,” he explained.
The implications of this trend are concerning. Siegel elaborates that a strain on the power grid can lead to a phenomenon known as “cascading failure.” When one part of the grid fails, the load is redistributed to other sections, ultimately leading to further failures. “We hope to avoid reaching that critical point, but history has shown us that such failures can spread through the electrical grid,” Siegel said.
Additional Stressors Beyond Heat
While extreme heat is a primary concern, it is not the only factor affecting power systems. “In certain regions of Canada, we’ve observed that lightning storms associated with high temperatures can spark wildfires, which further complicates the situation,” Siegel added. The interplay of various environmental factors is increasing the frequency and severity of outages.
On July 2, severe thunderstorms following the heat wave resulted in widespread outages across Ontario and Quebec, impacting thousands of residents. Emergency physician Edward Xie from the University Health Network cautioned that as air conditioning units are activated in response to the heat, the strain on the power grid escalates, heightening the risk of outages. “Individual buildings can also experience local power failures if their electrical supply becomes overloaded, which can disable air conditioning for many people at once,” he noted.
Preparing for Heat-Related Disruptions
In light of these challenges, experts are advising residents on measures to mitigate the impact of potential outages during extreme heat. Anabela Bonada, managing director of climate science at the INTACT Centre on Climate Adaptation, suggests practical steps for homeowners. “During peak heat hours, it’s advisable to keep windows and blinds closed to prevent hot air from seeping indoors,” she recommended.
If air conditioning units break down during a heat wave, Bonada advises using indoor air filters to maintain air quality and suggests opening windows in the cooler evening hours. “We are all placing considerable pressure on our electrical systems, which raises the likelihood of blackouts,” she warned. To avoid complications during heat waves, Bonada advocates for routine air conditioner maintenance, particularly in spring, to ensure systems are functioning optimally when temperatures soar.
Staying Safe in Extreme Heat
Health Canada stresses that heat stress affects everyone but poses the greatest risks to vulnerable populations, including the elderly, infants, and individuals with chronic health conditions. The agency encourages households to prepare emergency kits in anticipation of potential power outages. Essential items might include food, water, and battery-operated or wind-up flashlights.
Furthermore, Xie recommends strategies for staying cool, such as using window fans for ventilation and minimising strenuous activities. “Our bodies cool down by sweating, and airflow over the skin enhances this process,” he explained. Simple measures like wetting clothing or applying cool towels can also provide relief.
Why it Matters
The increasing frequency of extreme heat events in Canada not only endangers public health but also poses significant risks to the reliability of the nation’s power infrastructure. As climate change continues to exacerbate these conditions, proactive measures and public awareness are vital to safeguard communities against the consequences of heat-related power disruptions. Addressing these concerns is imperative for ensuring the resilience of our energy systems and protecting the health and wellbeing of all Canadians.
