Spatiotemporal Dynamics of Heatwave Vulnerability and Maternal–Child Health Risk in Zambia

Abstract Evidence on spatially differentiated heatwave exposure and heat-related vulnerability in sub-Saharan Africa remains limited. This study examines the spatial-temporal patterns of daytime, night-time and compound heatwaves in Zambia and their implications for maternal and child health vulnerability. Daily maximum and minimum 2-m air temperature from ERA5-Land reanalysis (1980–2024) were used to identify heatwave events on a grid-cell basis. Heatwaves were defined as periods of at least three consecutive days exceeding the local 90th percentile threshold (1981–2010 reference period). Heatwave frequency, mean duration and mean intensity were derived and summarized across Zambia’s agro-ecological regions (AERs). These metrics were integrated with demographic, environmental and health-system indicators to construct a composite Heat Vulnerability Index. The results show spatial differentiation in heatwave exposure aligned with AERs. AER I and IIb emerged as major heatwave-exposure and heat vulnerability hotspots. The south-central part of AER IIa also showed high heat vulnerability despite having a moderate heat exposure because it coincided with a wider spatial distribution of sensitive populations and low-moderate adaptive capacity. Mean temperature was strongly correlated with heatwave frequency ( r  = 0.86, p  < 0.0001) and duration ( r  = 0.81, p  < 0.0001), indicating that warming is associated more with repeated and sustained heat exposure than with intensity alone. El Niño years were associated with higher night-time and compound heatwave frequency. MAM ONI provided the strongest antecedent ENSO indicator of heatwave risk. Future studies should further examine the potential for using MAM ONI and seasonal weather forecasts for strengthening heat-health early-warning systems.