Eurasian river discharge into the Arctic Ocean has steadily increased during the 20th century, and many studies have documented the spatial distribution of trends. Different hypotheses have been proposed for different regions, which makes synthesis of the overall driver of the trend difficult. To explain an increase in annual streamflow, the obvious explanation would be trends in annual precipitation, but trends in annual precipitation are either absent or insufficient to explain the increase in streamflow. Some previous studies have demonstrated a possible link between winter precipitation and the snowpack and streamflow trends, and this study builds on this link to understand the role of winter precipitation and temperature trends on annual streamflow trends. We use both in-situ observations and a validated land surface model, showing consistent trends in both observations and model predictions of the snow water equivalent and streamflow. Model experiments demonstrate that the nonlinear interaction between winter precipitation and temperature result in a deeper spring snowpack that then results in overall positive runoff trends. Given that climate models consistently project increasing winter precipitation and warmer temperatures during the next century for northern Eurasia, these results underscore the importance in understanding how the projected changes will influence the seasonal snowpack. This may then have important consequences for streamflow in this region which could lead to increased freshwater export to the Arctic Ocean.