The Rio Grande Basin Study (Basin Study) is a stakeholder-led project funded through the U.S. Bureau of Reclamation that is developing climate adaptation strategies to address the growing gap between water supply and demand in the Upper Rio Grande Basin in Colorado, New Mexico, and Texas. The role of the USGS in the Basin Study is to simulate future streamflow using downscaled climate model projection data as input to the Upper Rio Grande Basin Precipitation-Runoff Modeling System (PRMS) (Chavarria and others, 2020). Simulated streamflow for 27 climate scenarios at 63 sites along the mainstem Rio Grande and its tributaries is used as baseline hydrologic response to climate-change emission scenarios and downscaling methods. This data release contains projected climate data (precipitation, maximum temperature, minimum temperature) from 27 climate scenarios used as input to PRMS, and PRMS simulated streamflow at 63 sites in the Upper Rio Grande Basin under each of the 27 scenarios.