Heat resilience assessment during a heatwave based on WRF-simulated UTCI: Insights from built LCZ types in Valencia, Spain

Driven by global climate change and rapid urbanization, urban development has been challenged by frequent occurrence of extreme events. As revealed by previous studies, the impacts of overheating varies individually and spatiotemporally, focusing on the latter, this study evaluated the outdoor thermal comfort across Local Climate Zones (LCZs) via two indices, Mean Radiant Temperature (Tmrt) and Universal Thermal Climate Index (UTCI). They were calculated based on meteorological parameters simulated by the Weather Research and Forecasting (WRF) model. Herein, a new Heat Resilience Index (HRI) was proposed based on UTCI and applied to a heatwave event in Valencia in July–August 2024. The developed index can effectively capture differences among LCZs, particularly in compact built types. Key findings include that despite the large intra-LCZ variations, LCZ 5/6/7/8 exhibit stronger HRI, while compact buildings (LCZ 1/2/3) show relatively lower HRI. Spatially, there is a trend observed in Valencia that HRI are higher in coastal areas. Both canopy-level (CUHI) and surfacelevel (SUHI) Urban Heat Island intensities were enhanced in LCZ 1/2/3 at night during heatwave period, with SUHI showing a greater magnitude. Benefiting from higher HRI, LCZ 5/6/8 did not exhibit CUHI during heatwave nights. Future work will focus on producing LCZ with improved accuracy and spatial resolution. Additionally, this framework will be applied in other cities to validate its accuracy and feasibility. This study provides a holistic assessment of urban heat resilience and identifies those LCZs have experienced stronger UHI while with lower HRI, offering valuable insights for improving urban resilience and sustainability. • Proposed a Heat resilience index (HRI) based on UTCI and meteorological parameters from WRF. • Coastal areas exhibited greater heat resilience. • Open/low-rise/sparse group (LCZ 5–9) have stronger heat resilience than compact group (LCZ 1–3). • Nighttime UHI was intensified during the heatwave in LCZ 1/2/3 due to their low HRI.