As a response to the increasing severity of extreme heat events in Toronto, the City is working together with Toronto Public Health (TPH) to optimize the City’s heat-response plan through implementing and upgrading Toronto’s Heat Health Alert System. Toronto’s Heat Health Alert System includes a three-day forecast outlook. This synoptic-based approach starts with an air mass categorization for each forecast day based on weather conditions (temperature, humidex, dew point, wind speed and direction, air pressure and cloud cover). Then an algorithm is run to predict the likelihood of excess mortality under these air mass conditions; it is this likelihood that determines whether the Heat Health Alert System forecasts an Extreme Heat Alert, a Heat Alert or neither.
As a response to the extreme heat events in the City of Toronto and given that Environment Canada projects Toronto will average 65 days per year where the average temperature exceeds 30°C, the City implemented a Heat Health Alert System (HHAS) in 2001. The HHAS issues a city-wide “Alert” when the likelihood of excess weather-related mortality exceeds 65 percent. The “Heat Alert” triggers several protocols, including the opening of seven designated cooling centres. Toronto’s Hot Weather Response Plan has contributed to increased awareness and the long-term safety of its population. Given the human health implications of prolonged heat exposure, especially for at-risk groups such as seniors, children, and individuals with pre-existing illnesses, the HHAS is considered a prudent action in building climate resilience.