With a unique biogeophysical signature relative to other freshwater sources, meltwater from glaciers plays a crucial role in the hydrological and ecological regime of high latitude coastal areas. Today, as glaciers worldwide exhibit persistent negative mass balance, glacier runoff is changing in both magnitude and timing, with potential downstream impacts on infrastructure, ecosystems, and ecosystem resources. However, runoff trends may be difficult to detect in coastal systems with large precipitation variability. Here, we use the coupled energy balance and water routing model SnowModel-HydroFlow to examine changes in timing and magnitude of runoff from the western Juneau Icefield in Southeast Alaska between 1980 to 2016. We find that under sustained glacier mass loss (-0.57 +/- 0.12 m w.e. a), several hydrological variables related to runoff show increasing trends. This includes annual and spring glacier ice melt volumes (+10% and +16% decade) which, because of high precipitation variability in the area, translate to smaller increases in glacier runoff (+3% and +7% decade) and total watershed runoff (+1.4% and +3% decade). These results suggest that the western Juneau Icefield watersheds are still in an increasing glacier runoff period prior to reaching ‘peak water.’ In terms of timing, we find that maximum glacier ice melt is occurring earlier (2.5 days decade), indicating a change in the source of freshwater being delivered downstream. Our findings highlight that even in climates with large precipitation variability, high latitude coastal watersheds are experiencing hydrological regime change driven by ongoing glacier mass loss.