Urban heat and soil sealing: A ten-year analysis of temperature dynamics in a semi-arid Mediterranean region

Soil sealing and urbanization significantly influence urban heat island (UHI) effects, particularly in semi-arid regions. This study examines the impact of soil sealing on urban temperature dynamics in Murcia, Spain, over a ten-year period (2008–2017). Using the UrbClim model and land use data, the analysis reveals that nighttime is the most critical period for heat retention, as sealed surfaces release stored heat. A 24 °C threshold for summer nights as a maximum temperature for human wellbeing underscores the severity of heat retention in urbanised areas, with city centres and industrial zones frequently exceeding this threshold, highlighting implications for public health and energy demand. During daylight hours, soil sealing has a reduced effect on temperature, as solar radiation affects all surfaces equally. In contrast, nighttime temperature contrasts between sealed and unsealed areas are substantial, driven by the inability of impervious surfaces to dissipate heat effectively. Seasonal variability further reveals that while the absolute UHI intensity peaks in summer, relative differences are notable in cooler seasons. Differences among artificial land uses also emerge, with urban cores experiencing higher mean temperatures than suburban areas due to limited vegetation and greater imperviousness. This study underscores the spatio-temporal variability of UHI effects and highlights the importance of understanding land use-specific contributions to urban temperature dynamics. These findings provide a basis for developing targeted strategies to mitigate UHI impacts and improve urban resilience to climate challenges. • The impact of soil sealing on urban temperatures in a semi-arid Mediterranean city (Murcia) was assessed over a ten-year period, highlighting hourly, seasonal, and spatial dynamics. • The analysis identifies nighttime as the period of peak heat retention in sealed areas, especially during summer and spring. • Hourly temperature variations were analysed to identify critical time slots for urban heat retention. • Findings reveal land use-specific temperature patterns, with city centres and industrial areas exhibiting the highest nocturnal heat retention. • The study provides insights into urban temperature variability, informing urban planning and climate adaptation strategies.