Data from included sources were extracted according to the research objectives, using data extraction templates (Supplementary Data Sheet 2). The EPHFs described in Canada’s Chief Public Health Officer’s 2022 report on mobilizing public health action for climate change were applied as a framework to report on the range of public health heat activities identified (Table 1) [2]. Narrative synthesis methods were used to characterize and compare public health roles in addressing extreme heat in each province, and to report on any evaluations of heat response activities.

The academic literature search yielded 6370 results (after duplicate removal), of which 26 articles were included for analysis (Supplementary Data Sheet 3: PRISMA diagram). Sixteen articles focused on extreme heat response in Quebec, eight in Ontario, and seven in BC (Table 3, and see Supplementary Data Sheet 4 for details). Of these, three articles focused on two or more provinces [25–27].

A total of 429 grey literature sources were retrieved across BC (n = 132), Ontario (n = 167), and Quebec (n = 130). These included informational text and graphic resources via webpages, reports (e.g., vulnerability assessments), protocols and guides, policy documents (e.g., legislation), and interactive tools such as heat maps, educational videos, and infographics. Publicly accessible heat strategies were limited: we identified 6 regional health system heat plans in Quebec, 8 municipal heat plans with public health involvement in Ontario, and 5 municipal heat plans with health authority involvement in BC.

The following sections detail how public health authorities in each province have developed and exercise their roles in responding to extreme heat. Provincial governments set standards and fund public health services, while public health units, departments, and agencies administer the programs.

Our review identified collaborative efforts to address extreme heat across organizations (horizontal collaboration), across levels of government (vertical collaboration), and across sectors (intersectoral collaboration). BC was the only province with a clear framework facilitating horizontal intersectoral collaboration at the provincial level through the BC HEAT committee, co-led by the BCCDC and BC Ministry of Health. Across all provinces, collaboration at local and regional levels was more common than at the provincial level, often spanning public health authorities, local governments, and other sectors and partner organizations (e.g., community organizations). Municipalities often lead these collaborations as part of their heat response plans, with public health authorities playing an advisory role [26, 37, 86, 87]. Examples of public health’s collaborative leadership include the Waterloo Region Extreme Heat and Cold Partnership [33] and North Bay Parry Sound District Heath Unit’s Extreme Heat Advisory Plan [34] in Ontario. Additionally, the Northern Ontario Climate Change and Health collaborative is a unique public health-specific network of seven PHUs seeking to collaboratively enhance their capacities to mitigate climate change health impacts [88].

In Quebec, many local public health departments co-lead heat response collaboration between regional and municipal civil security divisions [74, 83, 89]. For example, the Montreal regional public health department collaborates closely with the health system emergency unit (Coordination régionale des mesures d’urgence, de la sécurité civile et accès réseau) and the City of Montreal’s Civil Security Centre to plan population-level interventions and ensure alignment between the health system and the city heat response plans [26, 55]. Some public health authorities were observed to coordinate NGO partnerships to establish green spaces [90, 87], and to support seniors and individuals with mental health conditions measure indoor air temperatures [91].

Our review also identified examples of ‘vertical’ public health collaboration. Health Canada, the Public Health Agency of Canada, and the INSPQ regularly support the climate adaptation efforts of local public health authorities through expertise and ad hoc funding [92]. Notably, Health Canada finances multiple provincial and regional public health authorities conducting climate change health vulnerability assessments and heat response planning through the HealthADAPT program [49, 80, 92–94], and the recent HeatADAPT program [95].

Our review did not uncover any comprehensive evaluations of provincial or sub-provincial heat response strategies. Existing evaluations focus on specific response components or outcomes. Six evaluations were identified in Quebec, two in Ontario, and one in BC. Those in Quebec pertain to Montreal’s local heat response plan and provincial systems related to extreme weather. A 2007 evaluation of a public heat health education campaign by Montreal’s Public Health Department revealed a positive association between preventative messaging and adoption of preventative measures during heat events. The evaluation also highlighted that limited informational, financial, and social resources impeded the ability of high-risk seniors to adopt these measures [96]. A 2018 study analyzing the implementation of the Montreal heat response plan similarly found that while preventative measures were known and applied by healthcare personnel, their awareness and application was variable among vulnerable populations [97]. The study also highlighted the need to rapidly mobilize sufficient personnel as a central challenge of responding to heatwaves [97]. A related study from 2018 examined the validity of the term “vulnerable populations” in the Montreal heat response plan, finding that while individuals with schizophrenia do tend to view themselves as more vulnerable to heat, people with drug or alcohol addictions may not. The study also revealed that certain heat response interventions, such as targeted phone check-ins, were not always well received and could benefit from co-design with affected communities [98]. A 2016 quantitative evaluation found that the Montreal heat response plan helped to reduce mortality on hot days, with larger effects among elderly and low-socioeconomic status populations [99].

In 2017, an evaluation of the sensitivity and specificity of SUPREME in predicting heatwaves concluded that, while the system performed well, its sensitivity could be improved through minor adjustments to its alert criteria [100]. Finally, a 2016 evaluation of a selection of the urban heat island reduction projects funded by INSPQ found that some achieved significant cooling effects [63].

In Ontario, a population-based time series analysis of the impacts of the provincial Harmonized Heat Warning and Information System between 2012-2018 revealed a reduction in emergency department visits among certain populations, including those under 18 years of age, with co-morbidities, or living in rural communities, though the changes were not statistically significant [101]. Furthermore, a 2012 qualitative study on climate change adaptation efforts identified the need for provincial public health standards that explicitly address extreme heat mitigation and adaptation goals, and increased federal and provincial funding to support local adaptation strategies [43]. Study participants stated the importance of intersectoral collaboration to implement adaptation activities, such as multi-agency workshops to conduct extreme heat vulnerability assessments.

A 2025 BC study evaluated cooling centres across municipalities in Greater Vancouver through semi-structured interviews with public sector professionals [27]. Identified challenges included limited funding, staffing shortages, and infrastructure constraints. Opportunities to strengthen planning and operations include better collaboration across sectors and NGOs, improved outreach to communities, and harmonization of extreme weather responses.

Actors face multiple challenges in responding to extreme heat, including emergency workforce availability, identifying priority populations, sustained funding, political support, and effective communications [26, 96, 97, 104]. Recent studies have also highlighted ongoing gaps in governance to align work on climate emergencies [26, 104, 105]. Nevertheless, provincial guides and toolkits, vulnerability mapping, and cross-jurisdictional learning seem to support development and improvement of heat responses [26, 58, 65]. Targeted funds such as Quebec’s Green Fund also enabled the implementation of effective preventative measures such as urban greening projects and research supporting the advancement of heat strategies [59, 102]. BC’s extreme heat-targeted funding through the Community Emergency Preparedness Fund was initiated to support local governments and First Nations communities in extreme heat risk mapping and response efforts [106]. However, we could not uncover specific examples of how communities used this funding.

Published heat strategy evaluations remain limited in Canada. Our review found no comprehensive evaluation of provincial or sub-provincial heat strategies, and a related report found few HARS include an evaluation plan in Canada [21]. Existing evaluations focused on a single intervention or outcome of interest. This reflects a broader global trend of under-evaluation of heat responses [10]. Nonetheless, quantitative strategy evaluations identified in this review reported reductions in heat mortality and emergency department visits, for vulnerable populations in particular, and qualitative studies made recommendations for improvement of heat strategy components. Strategy evaluations are important for assessing both the effectiveness and quality of interventions in producing health outcomes, though collecting outcomes data and establishing causal links to heat strategy interventions remains challenging [10, 11]. However, strategies may be evaluated without relying on core measures and causal links, such as collecting data on alternative explanatory factors, and leveraging incremental plan changes to evaluate the impacts of new interventions [107]. Researchers could support more comprehensive evaluations, and partnerships across agencies can facilitate data sharing [107].

Furthermore, vulnerability to extreme heat is higher in certain populations depending on various biological, psychological, and socioeconomic factors [7]. Our review found that public health authorities across the three provinces conduct vulnerability assessments to identify populations at high risk to extreme heat, and convey information targeted to these populations. For example, public health authorities developed webpages and infographics specific to children, seniors, and workers [103, 108–112], and conducted targeted phone check-ins with at-risk individuals [98]. In this way, public health response to extreme heat aims to reduce inequitable heat health impacts. Nevertheless, one study demonstrated that groups identified as “vulnerable to heat” by public health authorities do not necessarily perceive themselves as such, and that targeted interventions are not always well-received [98]. This highlights the need for improved engagement of diverse populations in local heat response planning to prevent stigmatization and develop appropriate interventions [13]. Other studies have recommended greater efforts towards policy change to improve material and social conditions, reflecting broader calls to prevent heat and climate vulnerability by addressing socioeconomic and political structures as the primary drivers of vulnerability and inequitable heat impacts [13, 113]. International perspectives also support moving towards a collective approach to heat resilience and public health equity through community-based approaches and stronger intersectoral collaboration [11, 13, 113]. Moving toward such system-level approaches in close collaboration with high-risk communities could help mitigate the inequitable health effects caused by heatwaves by reorienting strategies toward addressing the root causes of vulnerability.

There are some limitations to this study. While nearly all public health authorities scanned provide extreme heat health information resources, many do not publish heat response plans, making it difficult to gauge the full extent of work being done. As a result, we reported public health responsibilities as outlined by provincial agencies, but were not always able to verify whether these are put into practice. Publishing public health strategies and plans would facilitate knowledge sharing across regions, as well as further research supporting continued strategy improvement [107]. We minimized the risk of reporting bias, a prevalent limitation of scoping reviews [114], by establishing data extraction templates that were used in all three cases (Supplementary Data Sheet 2).

This scoping review highlights how public health authorities across three Canadian provinces tend to play an advisory role within heat responses, though some are involved in coordination of efforts across sectors. While public health authorities appear primarily focused on downstream responsive heat-related activities, some public health leaders propose how the public health sector may also be critical to advancing upstream prevention and resilience. Our findings suggest there is room for public health authorities to further clarify and develop their role in addressing extreme heat impacts, including building meaningful collaborations with communities and across sectors.