Global warming amplified regional heatwave with nighttime preeminence outrun daytime heatwave

Abstract

Heatwaves pose a growing threat to human health and livelihoods, yet a comprehensive analysis of daytime and nighttime events across Africa remains lacking. This study provides a Pan-African analysis of observed and projected heatwaves, using percentile-based thresholds and multi-model climate projections. We find a significant increasing trend in heatwaves over recent decades, with a key novel finding: nighttime events are increasing more rapidly (6.23 days per decade) than daytime events (3.98 days per decade). Spatially, North Africa endures the most intense and prolonged heatwaves, while Southern Africa experiences the highest event frequency. This trend is projected to continue throughout the 21 st century, with scenarios (SSP1-2.6, SSP2-4.5, and SSP5-8.5) indicating a continued intensification and a persistent amplification of nighttime over daytime heatwaves. Under the high-emission scenario (SSP5-8.5), the continent is projected to experience an increase of 35–103 additional nighttime heatwave days in the near-future (2030–2060) and 110–118 days in the far-future (2070–2100), compared to an increase of (21–75 days and 82–113 days) for daytime heatwaves, respectively. Consequently, our findings consistently demonstrate that nighttime heatwaves are becoming and will continue to be more frequent, intense, and longer-lasting than daytime heatwaves. Therefore, these results underscore the urgent need for policymakers to develop integrated, multi-faceted adaptation and mitigation strategies that specifically address the distinct risks of nighttime heat in Africa. • Over the past 45 years, Africa has experienced a significant increase in heatwave frequency, duration, and intensity. • Nighttime heatwaves are becoming and will continue to be more frequent, intense, and long-lasting than daytime heatwaves. • North Africa endures the most intense and prolonged heatwaves, while Southern Africa experience the highest event frequency. • Atmospheric and soil moisture-precipitation feedback processes are the major driving forces behind significant heatwave trends in the region. • Under SSP5-8.5, nighttime heatwave days are projected to rise by 110–118 annually, vastly outpacing daytime increases.