While long-term rainfall trends and related atmospheric dynamics in eastern equatorial Africa (EEA) and central equatorial Africa (CEA) has been researched over the past several decades, much less is known about rainfall in western Uganda. This region is considered a rainfall transition zone between CEA and EEA. Using multiple rainfall and atmospheric datasets, this study examines the controls of and trends in seasonal rainfall across western Uganda for the 1983-2017 period. Rainy (dry) seasons were characterized by rising (sinking) air and increased (decreased) specific humidity. In addition, the tropical rain belt existed across CEA and not over EEA during the western Uganda rainy seasons. And wet days within rainy seasons have increased westerly flow from the Congo basin. Rainy seasons, especially the first rains, have gotten longer and wetter in all regions, and these changes are associated with increased rising air and specific humidity in the middle troposphere.