Mapping urban heat islands in Durban (2010–2025): A cross-sectional remote sensing study.

BackgroundUrban heat islands (UHIs) occur when built-up surfaces absorb and retain heat, causing higher temperatures in urban areas than in surrounding natural environments. Durban has undergone rapid urban expansion over the past decade, potentially intensifying UHI effects and increasing heat-related risks. Remote sensing provides a reliable method to monitor long-term surface temperatures and associated land-cover changes. This study mapped spatio-temporal UHI patterns in Durban between 2010 and 2025 and examined their relationship with land-cover transformation. Methods: A spatio-temporal remote sensing design was used. Landsat 7, Landsat 8 (USGS), and Sentinel-2 (Copernicus) satellite images were acquired for 2010, 2015, 2020, and 2025, focusing on dry-season scenes to reduce cloud interference. Land Surface Temperature (LST) was computed using mono-window and split-window algorithms. Land-cover classes were generated through supervised classification and validated using Google Earth reference points. Change-detection techniques quantified vegetation loss, built-up expansion, and temperature shifts. Spatial analysis in the Geographic Information System was used to examine the relationship between LST and land-cover type. ResultsSurface temperatures increased steadily between 2010 and 2025. The highest LST values were concentrated in the CBD, industrial areas, and rapidly urbanising townships. Vegetated spaces and coastal zones remained significantly cooler. Classification results showed a notable increase in impervious surfaces and a corresponding decline in natural vegetation. Hotspot maps confirmed a clear expansion of UHI zones over time, strongly linked to land-cover conversion from green space to built environments. ConclusionUrban growth in Durban has intensified UHI effects over the last 15 years. Built-up surfaces consistently recorded higher temperatures than vegetated and coastal areas, demonstrating the moderating role of green infrastructure. RecommendationsUrban greening, protection of remaining natural areas, and adoption of reflective or permeable building materials are recommended. Continued satellite monitoring should inform climate-adaptation and heat-risk mitigation planning.