Among the most vulnerable to the health-harming effects of heat are people experiencing homelessness. However, during the 2021 Heat Dome, the deadliest extreme heat event (EHE) recorded in Canada to date, people experiencing homelessness represented the smallest proportion of decedents (n = 3, 0.5%)—despite the impacted region (British Columbia) having some of the highest rates of homelessness in the country. Thus, we sought to explore the 2021 Heat Dome as a media-based case study to identify potential actions or targeted strategies that were initiated by community support agencies, individuals and groups, and communicated in the news during this EHE that may have aided in the protection of this group or helped minimize the mortality impacts. Using media articles collated for a more extensive investigation into the effects of the 2021 Heat Dome (n = 2909), we identified a subset which included content on people experiencing homelessness in Canada (n = 274, 9%). These articles were thematically analysed using NVivo. Three main themes were identified: (i) public warnings issued during the 2021 Heat Dome directly addressed people experiencing homelessness, (ii) community support services explicitly targeting this population were activated during the heat event, and (iii) challenges and barriers faced by people experiencing homelessness during extreme heat were communicated. These findings suggest that mass-media messaging and dedicated on-the-ground initiatives led by various organizations explicitly initiated to support individuals experiencing homelessness during the 2021 Heat Dome may have assisted in limiting the harmful impacts of the heat on this community.

It is critical to inform the public of the threat heat poses to health and provide actionable guidance on mitigating this risk before, during, and after heat events. To help educate the public during heat events, Health Canada works closely with Environment and Climate Change Canada (ECCC) to distribute heat-health messaging through a weather warning system. However, the warning system’s current list of messages dates back over a decade. Continually evaluating and updating messages is critical to ensure they are based on the best evidence available. A review was conducted to assess the existing heat-health messages and propose new messages based on recent empirical studies. The proposed messages were reviewed to ensure that readability and equity considerations were integrated. Academic, public health and meteorology experts across Canada reviewed the proposed messages and applied further revisions. The original list of heat-health messages included 12 messages. Based on the evidence and external reviews provided by 42 experts (academic: n = 9; public health: n = 22; meteorology: n = 11), messages were removed, merged, added and revised. The final list used by ECCC includes 30 messages. Health Canada’s heat-health messages disseminated through ECCC’s weather warning system were revised to ensure they are important, action-oriented, evidence-based, readable, equitable, regionally applicable, and timely. Ensuring these messages reflect current knowledge will be an ongoing and iterative process to support the public’s preparedness efforts to protect themselves and others during heat events.