Abstract: This article examines the relationship between climate change and political instability in Mirambo’s domain and in Buganda during the late-nineteenth century. It builds on the recent regional historiography that argues that both Mirambo and Mutesa I struggled to maintain their respective states’ integrity in their final years, before those states collapsed under new leadership from the mid-1880s. It does so by incorporating and adding to the latest climatological research on the region, and by analyzing the cascading effects of volatile levels of rainfall on agricultural yields and the spread of disease. It argues that the effects of frequent and severe droughts in 1876–84 were worsened by the adoption of high-potential-yield crops with low resistance to water stress, and by the growth of large administrative, commercial, and military centers, whose residents required feeding from production in rural areas, and which acted as reservoirs for epidemics. In turn, these effects contributed to population movements and they reduced states’ capacities to deal with regional rebellions, contributing to weakened political centers. This climatic and environmental context significantly contributed to political instability in at least two of equatorial eastern Africa’s most prominent states in the 1870s–80s.