Canada hasn’t been spared by heat waves, which have been growing more and more common across the globe. In Canada, climate change has caused an increase in the frequency and intensity of heat waves. This threat weighs on the health of the population, as oppressive heat is associated with increased mortality and many health problems. In the summer of 2021, British Columbia recorded 619 heat-related deaths. Of those, 93% occurred within the week of June 25 to July 1, during which temperatures in the village of Lytton reached a high of 49.6° C.

Exposure and vulnerability to heat waves vary over time and across space, which leaves some groups at greater risk. A study of the impact of the heat wave that affected the region of Laval (Quebec) from June 29 to July 5, 2018, showed that people living in high-vulnerability areas were 1.5 times more likely to die than those living in less vulnerable areas.

The impact of heat waves on the health and well-being of individuals in a community depends predominantly on their access to resources— particularly adequate housing. Governmental and non-governmental organizations, whether local, regional, or provincial, must contend with the social and economic repercussions of climate change.

Geographic data are particularly useful when it comes to identifying and mapping vulnerability across time and space. They also contribute to a better understanding of the underlying processes of vulnerability, facilitating the development of more effective mitigation strategies. Decision makers and citizens alike benefit when knowledge gained from research is made more broadly available, thus making the decision-making processes, the setting of standards, and the establishment of procedures, at a local and regional level, more concrete.



The objective of this project is to develop an interactive online mapping application which provides accurate information about the geographic distribution of the vulnerability and exposure of major Canadian communities to heat waves while also specifying, for each geographic unit, the intensity of these weather events.

In our view, such tools give the public meaningful and context-appropriate information for a geographic analysis of the vulnerability of communities living in Canada’s major urban centres. With this information, public authorities will be better equipped to deal with heat waves and the health effects they can cause.

Study area

Our project covers 156 census metropolitan areas (CMAs) and census agglomerations (CAs) throughout Canada. The indicators were calculated for the 2021 census dissemination areas, which are the smallest standard geographic areas for which all Canadian census data have been published. Typically, between 400 and 700 people live in a dissemination area. Moreover, because we wanted to represent the population’s exposure and vulnerability at the finest scale possible, that is, the environment where individuals reside, a dasymetric mapping* of the ecumene was applied to the dissemination areas to identify and exclude uninhabited areas.

*Dasymetric mapping is a cartographic technique used to accurately represent statistical data by taking into account the actual shape and size of the area under study, rather than distributing it uniformly within these areas, as is the case with maps that map an entire region regardless of whether or not there are dwellings in the area.

Project execution

The mapping of Canadian communities’ exposure and vulnerability to extreme heat waves was carried out by a research team from Université Laval’s department of geography.