Assessing heat-related health risk in Ghana using bioclimatic indices

Abstract

Climate change is driving rising temperatures worldwide, intensifying the risk of heat-related illnesses such as heat stress, heat stroke, and exhaustion. In Ghana, however, the health risks associated with extreme heat are often underestimated, as most existing assessments rely on subjective perceptions rather than scientifically validated indices. This study addresses this gap by assessing heat-related health risks across Ghana using the Universal Thermal Climate Index and Humidex. Hourly temperature and relative humidity data were extracted from the ERA5 reanalysis dataset to compute bioclimatic indices across all agroclimatic zones. The results show widespread warming across the country, with minimum temperatures increasing more rapidly than maximum temperatures. The Sudan and Guinea Savannah zones experience the highest levels of thermal stress, while declining humidity in the Forest zone further exacerbates discomfort. Seasonally, the greatest risks occur between November and May, peaking in March and April, and diurnally, exposures are most severe between 11:00 and 17:00 h. These findings demonstrate that extreme heat is an escalating public health threat in Ghana, particularly in the Sudan and Guinea Savannah zones. The study highlights the urgent need for adaptation measures such as public awareness campaigns, heat early-warning systems, and climate-resilient cooling infrastructure. By providing robust, index-based evidence, this work contributes valuable insights for policymakers, urban planners, and public health authorities to design effective strategies that protect vulnerable populations from the growing health impacts of climate change. • Minimum temperatures are rising faster while relative humidity is declines. • Heat-related health risks are highest in north and lower in the south. • Greatest heat danger occurs Nov–May, especially between 12 and 3 PM. • Public awareness, early warnings, and cooling systems are urgently needed.