This study examines near-surface air-temperature variability during extreme heatwaves in Coimbra (Portugal), focusing on Urban Heat Island (UHI) dynamics through a hotspot-based assessment of intra-urban thermal hotspots (IUTHs), defined as localized zones of recurrent elevated near-surface temperatures. Using an extensive multi-site dataset collected at multiple times of the day across heterogeneous urban environments, the analysis evaluates how urbanization intensity, surface cover, green infrastructure, and site-specific context influence diurnal temperature contrasts and patterns of heat exposure. Statistical results reveal clear spatial thermal disparities, with densely built-up and highly impervious areas such as Santana and the Seminary surroundings consistently emerging as intra-urban hotspots, particularly during afternoon peak temperatures. In contrast, green spaces (Botanical Garden and Mermaid Garden) act as cooling refugia, exhibiting lower near-surface air temperatures and reduced thermal amplitude compared with surrounding urban areas. Proximity to water bodies further moderates ambient conditions, highlighting the buffering role of blue infrastructure during extreme heat periods. These findings demonstrate that analysing UHI intensity through fine-scale intra-urban hotspot patterns provides valuable insights for urban climate adaptation. The results support the strategic integration of green spaces and nature-based solutions in urban planning to mitigate heat risk, strengthen climate resilience, safeguard public well-being, and promote more adaptive and liveable cities.
Ornelas et al. (Wed,) studied this question.