The Heat Alert System

How does the heat health alert system work?

From May 15 to September 30 of each year, Toronto Public Health staff monitors the Heat Health Alert System to determine when the Medical Officer of Health should declare a Heat or Extreme Heat Alert. Using spatial synoptic classification, the Heat Health Alert System compares forecast data to historical meteorological conditions which have in the past, lead to increased mortality in Toronto.

Forecast data includes weather conditions such as temperature, dew point, humidity, cloud cover, wind speed and direction. The system also considers the number of consecutive days oppressive conditions occurred.

Heat Alert is when forecast weather conditions suggest that the likelihood of a high level of mortality is between 25 and 50 percent greater than what would be expected on a typical day.

Extreme Heat Alert is when forecast weather conditions suggest that the likelihood of a high level of mortality is at least 50 percent greater than what would be expected on a typical day.

What happens during a heat alert?

Once the Medical Officer of Health declares a Heat Alert, notification of key response partners, community agencies and the public is initiated. Hot weather response activities focus on protecting vulnerable groups at increased risk for heat-related illness. Information on the response activities provided by the City and community partners during a Heat Alert is outlined in the City of Toronto Hot Weather Response Plan.

What happens during an extreme heat alert?

In addition to the services provided during a Heat Alert, the City opens seven cooling centres when an Extreme Heat Alert is declared. Water and light snacks are available at the seven cooling centres.

As well, during Extreme Heat Alerts:

  • Parks, Forestry and Recreation may extend operating hours of certain City pools.
  • Toronto public health inspectors during extended heat events will visit known rooming houses, boarding homes and other residential premises of concern to determine if the recommended Hot Weather Protection Plan has been implemented at the building.

Toronto's Hot Weather Response Plan

The City of Toronto Hot Weather Response Plan is a protocol for hot weather response which aims at reducing the incidence of heat-related illness and death in Toronto, due to extreme heat. The main focus of the plan is to provide education and services to vulnerable groups at increased risk for heat-related illnesses.

Learn more about the Hot Weather Response Plan 2012 (PDF).

Board of Health Reports

Last updated March 2012