Mapping the urban heat island and climate risk in Padua (Italy): Trends in extremes and perspectives for climate justice in adaptation planning

The Mediterranean Basin is widely recognized as a prominent hotspot of climate change impacts. Extreme meteorological events, such as heatwaves (HWs), exacerbate the urban heat island (UHI) effect, thereby increasing climate risks, particularly in high-density urban areas. This study examines the spatial distribution and temporal evolution of UHI, and heat-related climate extremes in Padua, a medium-sized city in the Po Valley (Italy) that is increasingly exposed to thermal stress. An integrated approach, combining the high-resolution UrbClim model data and meteorological observations, even from citizen-science weather stations, is used to assess climate trends, intra-urban variability, and heat-related risks associated with hot days (HDs) and tropical nights (TNs). Over the 2008–2017 period, most of the municipal area experienced on average 50 HDs per year, while more than 50% of the territory recorded over 60 TNs, with peaks exceeding 80 nights in the city centre and industrial districts. This indicates that approximately half of the days were affected by critical thermal conditions during the warm season. As the most vulnerable areas coincide with densely populated neighbourhoods characterised by limited green infrastructure, the study introduces a risk assessment that explicitly accounts for vulnerable population groups, including children, old and foreign residents. The findings highlight the substantial impacts of extreme heat on both the urban environment and its inhabitants by providing a detailed assessment of population exposure. These results provide a tool supporting the development of future heat hazard scenarios and targeted adaptation strategies.