This study investigates thermal dynamics of tropical rivers influenced by dams, focusing on the Rajang and Baleh rivers in Sarawak, Malaysia, and the Semeniyh and Sompo rivers in Peninsular Malaysia. It compares satellite and UAV-based observations to assess thermal variations downstream of dams. Results show that UAVs capture finer-scale thermal heterogeneity than satellites, with stronger correlations and higher spatial resolution. The study highlights significant thermal changes in the Rajang River due to dam operations, with altered seasonal variability. It underscores the need to integrate satellite and UAV data for effective ecological monitoring and management of thermal dynamics in tropical rivers.