Every summer, heat waves affect several regions of Quebec, particularly in the south of the province. These events are characterized by very high temperatures, both day and night, for several consecutive days. They have significant effects on health and they reduce quality of life, particularly in the most vulnerable populations.
Currently, summer 2025 seems to be no exception. In late June, Montréal experienced its first heat wave over the Saint-Jean-Baptiste long weekend, with temperatures reaching 34°C and 35°C on June 23 and 24. Several extreme heat events followed: from July 11 to 17 (except the 14th), the temperature went above 30°C every day, often accompanied by oppressive humidity. The summer continued with notable heat in August. In Montréal, for example, temperatures exceeded 30 °C for at least six consecutive days. On August 10 and 11, heat records dating back to 1944 were broken, with temperatures reaching 34.4 °C and 35.1 °C in the city.
Given that heat waves are becoming more frequent and intense due to climate change, urban greening is emerging as a natural, effective solution to cool our towns and cities and mitigate the impacts of extreme temperatures.
Green solutions for cooler cities
For several years now, municipalities across Quebec have expanded adaptation initiatives to add greenery and reduce heat. Creating urban cool islands to lower ambient temperatures is one of the main measures taken to adapt to heat waves.They are particularly necessary in dense and disadvantaged neighbourhoods, which often lack vegetation. This also applies to areas with more impermeable surfaces like parking lots, asphalt streets and buildings, which store and radiate heat.
To achieve this, communities are using various adaptation strategies that bring nature into the city. For example, municipalities can increase tree planting along streets or in parking lots to create shaded areas that help lower temperatures. They can also install green roofs and green walls on public buildings and schools, which act as natural air conditioners.
Some municipalities are even completely rethinking the layout of their neighbourhoods to integrate green infrastructure such as rain gardens and bioretention basins. These installations not only improve stormwater management, but also reduce the effects of hot weather by cooling the ambient air. The creation of new green spaces, such as parks, green corridors and riverside paths, is another suitable adaptation measure. In addition to cooling the air, they improve air quality, enrich urban biodiversity and beautify the landscape.
Additional adaptation measures to cope with heat waves in cities
Beyond greening, communities can also design and improve their municipal infrastructure to resist hot weather by modernizing insulation, ventilation and air conditioning systems.
Extending the opening hours of public spaces where people can cool down on very hot days, such as swimming pools, splash pads, libraries and community centres, is also an adaptation measure.
The OASIS program
The Quebec government’s OASIS program recognizes the need for municipalities to implement greening measures and helps them take action. The program provides municipal organizations and Indigenous communities with up to $29 million of financial support to carry out greening projects with the aim of adapting to climate change.
With three components focusing on the planning, implementation and maintenance of greening projects or green infrastructure, this program aims to reduce the impacts of heat waves and other climate hazards by using nature as an ally. Several municipalities in Quebec have already benefited from this funding to accelerate the implementation of adaptation measures.
Heat waves, which are increasing in frequency and intensity in several regions of Quebec, require a collective, coordinated response. Urban greening, supported by programs like OASIS, helps adapt our living environments to limit the effects of high temperatures and make our infrastructure more resilient.
The combination of individual prevention measures and warning systems such as Conseils climat helps protect the public during and after a heat wave. Investments that leverage natural processes to cool our streets, shade our buildings and enhance our green spaces improve our living spaces today and increase our resilience for a cooler, healthier future for everyone.
What is a heat wave?
According to the Institut national de santé publique du Québec (INSPQ), a heat wave occurs when maximum daytime temperatures reach or exceed a threshold between 31°C and 33°C and minimum nighttime temperatures remain between 16°C and 20°C for three consecutive days. These thresholds vary by region and are based on the associated excess mortality risks. For example, southern regions have higher thresholds than the northern and eastern regions of Quebec.
