Toronto Public Health issues warnings for high heat or humidity that is expected to last two or more days. During this time, heat warning information will be updated daily to reflect the current status. Toronto Public Health follows a provincial Harmonized Heat Warning and Information System for dealing with heat events in the City of Toronto.

Toronto Public Health staff will monitor this system to determine when the Medical Officer of Health should declare a heat warning or extended heat warning. This coordinated provincial system provides a consistent approach for processing and issuing heat warnings in Ontario. It also provides evidence-based heat warning triggers which are based on the association between temperature, humidex and mortality.

Check on Family, Friends and Neighbours

During heat warnings and extended heat warnings, please call or visit family, friends and neighbours, especially isolated seniors.

Other groups at risk include:

  • people with chronic and pre-existing illnesses
  • infants and young children
  • people on certain medications
  • people who are marginally housed or homeless