Assessing urban heatwave vulnerability through a multiscale and multicriteria GIS-based approach: Evidence from three Spanish cities

As climate change intensifies, heatwaves are becoming more frequent and severe, increasing risks for urban populations. This study presents a multiscale and multicriteria GIS-based methodology for assessing urban heatwave vulnerability, grounded in the IPCC framework and applied to three Spanish cities: Bilbao, Madrid, and Caceres. A key innovation lies in evaluating vulnerability at two spatial scales—buildings and open public spaces—which captures the existing interaction between them. The assessment integrates expert-defined indicators, AHP-based weighting and value function normalization, addressing constructive, socioeconomic, cultural and environmental factors. The methodology produces vulnerability maps that reveal spatial patterns and inform climate adaptation priorities for decision support. The results show that heatwave vulnerability is highly uneven within cities and strongly shaped by both the socioeconomic profile of the population and the characteristic of the urban fabric. The approach is transparent, scalable and adaptable, providing a valuable tool for urban heat waves adaptation and resilience planning.