Climate variation is known to affect human health in developing countries. This paper quantifies the impact of variations in precipitation and temperature on the regional prevalence of diarrhea in children under the age of three in Sub-Saharan Africa. Demographic and Health Survey data for the regions of 14Sub-Saharan African countries are matched at fine resolution with climate data from the Africa Rainfall and Temperature Evaluation System (ARTES) for the period between 1992 and 2001. The results show that shortage of rainfall in the dry season increases the prevalence of diarrhea across Sub-Saharan Africa. Such shortages occur in many regions when rainfall is average and low relative to the long-term average for that month. The results also show that an increase in monthly average maximum temperature raises the prevalence of diarrhea while an increase in monthly minimum temperature reduces diarrheal illness.