Urban Form and Climate Resilience: Understanding the Heat Island of Patras, Greece

The rapid expansion of cities, combined with the increased frequency and intensity of droughts and heatwaves in the Mediterranean region, have made Urban Heat Islands (UHI) widespread. Here, focusing on the city of Patras, the third largest city of Greece, we analyzed the spatiotemporal patterns of urban land surface temperature during summertime, and we quantified the relationships between temperature and geomorphological (e.g., elevation, slope) and urban (e.g., building height, road network density) features. The delineation of UHI was maded using Land Surface Temperature (LST) data from 2018 to 2025 based on the NASA’s ECOSTRESS mission. This dataset provides high-resolution (70 x 70m) thermal infrared imagery with diurnal coverage, thanks to its irregular temporal sampling. In-situ air temperature data available from a network of urban meteorological stations were also used to verify the spatiotemporal patterns of temperature variability. At the daily time scale, no clear links were found between daily summer-time temperature and urban and topographic features. However, when data were analyzed at the diurnal time scale, clear dependences between hourly temperature variability and urban features were revealed. More specifically, building and road density, as well building height, exerted low correlation with temperature during morning hours, with this cross-correlation becoming positive during late afternoon and evening hours, i.e., areas with denser urban fabric showed higher evening temperature values. Regarding green spaces, as quantified with the values of the NDVI index, the correlation with hourly temperature was low during daytime, yet, this cross-correlation became significantly negative during nighttime, i.e., areas with higher values of NDVI showed a rapid decrease in nighttime temperature values. The obtained results link the spatiotemporal variability of land surface temperature over the city of Patras with key urban and topographic features and provide valuable insights towards targeted interventions enhancing the overall resilience of the city to future climatic stressors.