These data were used to examine drivers behind changes in water temperature downriver of dams across the western U.S. from 1995-2015 and the influence of such changes on rainbow trout recruitment and rainbow and brown trout adult length. First, we linked reservoir storage capacity and dam size to the warmest monthly water temperature per water year (WY) to assess the influence of low storage capacity (shallow reservoirs) on downstream water temperature. We then took results from previously published Generalized Linear Mixed Models (GLMM) that assessed the influence of physical and biological predictors (e.g., flow, trout density, reservoir metrics) on trout recruitment and adult size and added mean annual, maximum annual, and minimum annual water temperature and the warmest and coldest month in each WY to the dataset. This permitted an evaluation of the relative importance of water temperature on trout population dynamics relative to other physical and biological predictors. Detailed methods and results are reported in the manuscript associated with this data publication.