Permafrost distribution significantly affects groundwater flow patterns and exchange between groundwater and surface water. This is especially true in mountainous catchments, where permafrost distribution often depends on factors like local topography, vegetation, and ground composition. Furthermore, anthropogenic climate change is amplified at high latitudes and high elevations where permafrost occurs, and resultant land surface warming is expected to alter permafrost distributions in the near future, as well as over very long time scales. During these climate transition periods, permafrost occurrence and extent will diminish, opening new flow paths for groundwater and increase connectivity with surface water. Conversely, during far-future cooling climate scenarios, permafrost formation is expected, impacting groundwater � surface water interactions in ways currently not well understood. In this study, a three-dimensional numerical groundwater-surface water model was constructed with FEFLOW for the mountainous Wolf Creek Catchment in the discontinuous permafrost zone in the Yukon. Investigations of groundwater travel times revealed that the local distribution of permafrost plays a significant role, with increased groundwater travel times in permafrost areas. Furthermore, model runs based on future cooling scenarios with more extensive permafrost resulted in increasing groundwater travel times with permafrost extent. The modelling approach also underlined that groundwater flow in mountainous permafrost environments is best understood in three dimensions, and that exchange between groundwater and surface water exhibits significant spatial variability depending on local topography and permafrost presence. The results further underline the complexity of groundwater flow patterns in permafrost environments, especially mountainous catchments, in which permafrost distribution can vary significantly.