Evaluating the Urban Heat Island Effect in Montreal: Urban Density, Vegetation, Demographic, and Thermal Landscape Analysis

Montreal experiences a significant urban heat island (UHI) effect, potentially intensified by its dense urban structure, varied vegetation, and demographic distribution, leading to substantial outdoor thermal discomfort, especially during heatwaves. To quantify this, measured thermal landscape data were analyzed over several months in Montreal, including heatwave periods, and outdoor thermal comfort was assessed using the humidex, discomfort index, heat index, and temperature–humidity index. The results indicated notable temperature and humidity variations across the city, with the exceedance of thermal comfort index thresholds being significantly higher during heatwaves (humidex: 10.83%, discomfort index: 53.33%, heat index: 24.77%, temperature–humidity index: 36.67%) compared to normal periods. This study provides a quantitative evaluation of UHI-induced outdoor thermal discomfort in Montreal, emphasizing its severity during heatwaves and analyzing the influence of urban density, vegetation, and anthropogenic emissions, thus offering valuable insights for urban planning strategies to mitigate public health impacts.