Spatio-temporal quantification of urban heat islands in Lusaka city

Rapid, unplanned, and uncontrolled urbanisation has contributed to ecological damage worldwide, including elevated land surface temperatures (LST), intensified Urban Heat Island (UHI) effects, and the growing risks to environmental and human well-being. Although these challenges are increasingly evident in African cities, there is limited understanding of their spatial and temporal dynamics in rapidly urbanising contexts. This study demonstrates a geospatial framework for assessing the spatial and temporal characteristics of the UHI effect, using Lusaka City as a case study. The framework combines Landsat 5, 8, and MODIS imagery to analyse 25 years of LST dynamics across winter and summer conditions, and between daytime and night-time periods. Urban-rural temperature gradient analysis, UHI intensity estimation, and LST-land cover relationship analysis were used to examine characteristics, drivers, and temporal variability of the phenomenon. The results reveal that urban areas exhibit lower daytime LSTs than surrounding rural areas, whereas the opposite pattern is observed at night. Over time, winter LSTs decreased slightly (~Δ0.2°C), while summer LSTs increased substantially (~Δ6°C), indicating an intensifying warming trend, with faster increase in urban LSTs. Strong positive correlations were found between LST and bare land and impervious surfaces. The findings suggest that in the absence of effective mitigation, Lusaka’s summer LSTs are likely to continue rising with implications for thermal discomfort, environmental sustainability and urban resilience. The study provides a transferable geospatial framework for assessing UHI dynamics in data-scarce and rapidly changing urban environments, while offering evidence-based insights to support green infrastructure planning, land use management, and climate adaptation.