Analysis of Urban Heat Island Effect in Aba, Abia State

Urban heat islands represent a significant thermal comfort and public health challenge in densely built Nigerian cities, and their characterisation in secondary cities like Aba is essential for developing evidence-based mitigation strategies in urban planning and architecture. This study analyses the urban heat island effect in Aba, Abia State, by comparing air temperatures recorded across commercial, residential, and peri-urban green areas at standardised monitoring intervals. Temperature and humidity data were recorded using twelve calibrated HOBO data loggers deployed across a stratified set of urban locations over a four-week period encompassing both dry and wet season phases. Land use and land cover classification using satellite imagery was conducted to correlate surface characteristics with measured temperature differentials. Results demonstrate a mean urban-rural temperature differential of 3.6 degrees Celsius during evening hours, intensifying to 5.1 degrees Celsius on clear, low-wind days. The highest temperatures were recorded in the Ariaria Market commercial area, characterised by high impervious surface ratios exceeding ninety percent and minimal tree cover. Residential areas with moderate tree coverage showed intermediate temperatures, while the Aba River riparian corridor provided measurable cooling by as much as 2.8 degrees Celsius relative to adjacent built areas. The study confirms that vegetation removal, dense building configurations, and extensive paved surfaces are the primary drivers of Aba's urban heat island. Recommendations include mandatory tree planting in commercial development approvals, cool roof incentives, and a riverside green corridor enhancement programme aligned with the Abia State Urban Development Strategy. Keywords: urban heat island, thermal comfort, urban greening, Aba, Abia State.