Stream ecosystem metabolism modulates organic carbon (OC) cycling in rivers and regulates downstream OC fluxes. Climate-change scenarios predict precipitation to shift from snow towards rain in alpine ecosystems, however consequences of this shift to stream metabolism are poorly understood. Using 18-months of continuous metabolism estimates encompassing two winters with ‘high’ (1807 cm) and ‘low’ (407 cm) snow accumulation, we studied effects of snowmelt hydrology on stream ecosystem metabolism across 12 sites in an Alpine network (Ybbs River, Austria). Net ecosystem production (NEP) ranged from -41.3 to 15.7 g O2 m-2 d-1 across the network. Times of autotrophy coincided with spring snowmelt but the inter-annual comparison of spring metabolism indicated reduced snowmelt shifted metabolism towards heterotrophy. Catchment size and the variation of snowpack (‘high’ versus ‘low’) across the elevation gradient drove this shift in NEP. Furthermore, inter-annual carbon spiralling turnover lengths decreased, resulting in increased OC loss likely due differences in stream discharge and respiration. We suggest that metabolism in alpine streams respond to precipitation changes by shifting from autotrophy to heterotrophy during spring and potentially from CO2 sinks to sources.