Groundwater discharge influences surface water thermal regimes, but the thermal impact partly depends on the nature of groundwater discharge patterns. Streams dominated by diffuse groundwater discharge typically exhibit modulated thermal regimes, while streams characterized by spatially focused groundwater discharge can exhibit pronounced spatial thermal variability. Stream thermal regimes modulated in time impose less thermal stress on aquatic biota, and enhanced spatial thermal variability creates riverscapes with thermal refuges (i.e., cold-water plumes) that sustain cold-water organisms during heat waves. Process-based stream temperature models often represent the thermal effects of groundwater discharge by implicitly or explicitly invoking several assumptions about groundwater discharge, including the aquifer source depth, discharge temperature, climate sensitivity, and spatial discharge patterns. Such assumptions may be necessary given the paucity of groundwater-surface water interaction data and may be reasonable when groundwater only exerts minimal influence on stream temperature. However, where data exists, properly accounting for the present-day and future thermal impacts of groundwater discharge in process-based stream temperature models is possible. We draw from a recently published review article to (1) advance process-based understanding of the thermal impacts of groundwater discharge on streams and (2) evaluate approaches for representing these processes in stream temperature models.