Research on climate change and human population growth has focused mainly on how population size affects greenhouse gas emissions. Much less is known about how changes in temperature and precipitation, and corresponding socioeconomic impacts, influence population growth despite plausible rationale for such effects. We examine this relationship using birth histories from 1982 through 2017 in 23 sub-Saharan African countries, combined with high-resolution historical climate records. Our analyses show that exposure to climatic variability is associated with changes in the probability of childbearing, at least in the short run. Women exposed to spells of above-average temperatures and below-average precipitation experience significant reductions in the probability of fertility in the subsequent year. The association between precipitation anomalies and birth rates is particularly robust, though the estimated magnitude of effects is modest. We find substantively meaningful variation in both temperature and precipitation effects between demographic groups and across countries. Our results underscore the need to consider changes in fertility among the adaptive strategies households will employ in the face of environmental change. They also highlight the need to incorporate feedbacks between climate and fertility in models of population change and greenhouse gas emissions.