Shelter, Support and Housing Administration

Harmonized Heat Warning and Information System

How does the Harmonized Heat Warning and Information System work?

Prior to this year, Toronto Public Health participated in a pilot Provincial Harmonized Heat Alert and Response System (HARS).  With the success of that project, the program was fully implemented in 2016.  The criteria for issuing warnings was selected after an extensive review of epidemiological evidence led by Public Health Ontario and Health Canada about the links between temperature, humidity, and health outcomes including mortality and illness.

Toronto Public Health receives weather forecasts from Environment and Climate Change Canada (ECCC) in advance of issuing a Heat Warning.  Extended Heat Warnings are issued if conditions are forecasted to continue for 3 or more days.  Heat warnings from Environment Canada are based on the following triggers:

Forecast Temperature High (°C)
Forecast Temperature Low (°C) Forecast Humidex Duration (days) Action
≥31 ≥20 ≥40 2 Medical Officer of Health will issue a Heat Warning
≥31 ≥20 ≥40 3+ Medical Officer of Health will issue an Extended Heat Warning

What happens during a heat warning?

Once the Medical Officer of Health declares a Heat Warning, 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 Warning is outlined in the City of Toronto Hot Weather Response Plan.

The City also opens seven cooling centres when a Heat Warning is declared.

What happens during an extended heat warning?

In addition to the services provided during a Heat Warning, all cooling centres remain open when an Extended Heat Warning is declared. During this time, water and light snacks are available at the seven cooling centres.

As well, during Extended Heat Warnings:

  • Parks, Forestry and Recreation may extend operating hours of certain City pools.
  • During extended heat events, Toronto Public Health Inspectors 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.

Board of Health Reports