Mountain snowpacks will melt earlier due to climate change, affecting streamflow timing. A new method using daily streamflow cycles shows that snowmelt-driven streamflow is more sensitive to climate change than previously thought. Warmer basins have earlier snowmelt, and colder watersheds are more sensitive to warming. The projected changes in streamflow timing are more accurately predicted using the new method compared to traditional land surface models. This research suggests that understanding diel streamflow cycles can help improve predictions of how climate change will impact streamflow and water resources.