Seasonal variations of the surface urban heat island in the semi-arid region of Khartoum State, Sudan, using Landsat-derived LST data

Purpose This study investigates the spatiotemporal and seasonal variations of land surface temperature (LST), surface urban heat island (SUHI) intensity, and the urban thermal field variance index (UTFVI) in Khartoum State, Sudan. The study aims to characterise seasonal thermal patterns and identify areas experiencing greater thermal stress to support climate-responsive urban planning and heat mitigation. Design/methodology/approach Google Earth Engine (GEE) was used to process Landsat-5 and Landsat-8 imagery acquired between 1988 and 2023. LST was derived from thermal observations, while SUHI intensity was assessed to examine spatial and temporal thermal contrasts. UTFVI was used to evaluate spatial variations in thermal stress during summer, autumn, and winter. Thirty representative locations across the major urban centres were also analysed to assess local variations in thermal conditions. Mann-Kendall trend analysis and Sen's slope estimation were applied to assess temporal trends in seasonal mean UTFVI. Findings The results showed substantial seasonal and spatial variations in LST, with the highest temperatures occurring during summer. Summer LST ranged from 54.4°C to 67.8°C, with higher values generally observed over exposed bare-land areas and urban outskirts. SUHI intensity varied spatially and seasonally, with the highest intensity of 5.57 recorded during summer 2002. UTFVI showed substantial seasonal and interannual variability, with greater thermal stress generally observed in urbanised and exposed bare-land areas, while vegetated and riverine areas exhibited lower thermal stress. Mann-Kendall analysis indicated no statistically significant monotonic trend in UTFVI for summer, autumn, or winter (p > 0.05). These findings highlight the importance of vegetation and water bodies in moderating surface thermal conditions and provide useful evidence for climate adaptation and heat mitigation in semi-arid urban environments. Originality/value This study provides a comprehensive multi-decadal (1988–2023) and seasonally resolved assessment of LST, SUHI, and UTFVI in Khartoum State using consistent Landsat data and the Google Earth Engine platform. Unlike previous studies limited to short-term or station-based analyses, it integrates spatial, temporal, and seasonal perspectives in a semi-arid urban environment. The research reveals that peak thermal stress occurs not only in urban cores but also in surrounding bare lands, challenging conventional SUHI assumptions. By linking land cover characteristics with thermal patterns, the study offers valuable insights for climate-sensitive urban planning and heat mitigation strategies in data-scarce regions.