Projections of regional changes in seasonal surface-air temperature and precipitation for the eastern and western Zambezi River Basin regions are presented. These projections are cast in a probabilistic context based on a numerical hybridization technique of the MIT Integrated Global System Model. Unconstrained emissions send the majority of outcomes in spring precipitation to a drying by 2050, although the total distribution spans both precipitation increases and decreases. From climate policy, the distributions’ range collapse considerably and the distributions’ mode lies near zero precipitation change. For surface air temperature, the most notable effect of climate policy is to reduce the mode value of warming as well as the occurrence of the most extreme increases.