Quantification of climate forcing of glacial hydrological systems at the decadal scale are rare because most measurement stations are too far downstream for glacier impacts to be clearly detected. Here, we apply a measure of daily hydrograph entropy to a unique set of reliable, high altitude gauging stations, dating from the late 1960s. We find a progressive shift to a greater number of days with diurnal discharge variation as well as more pronounced diurnal discharge amplitude. These changes were associated with the onset of rapid warming in the 1980s as well as declining end of winter snow depths as inferred from climate data. In glaciated catchments, lower winter snow depths reduce the magnitude and duration of snowpackbuffering and encourage the earlier onset of glacier ice exposure, with associated lower surface albedo and more rapid melt. Together, these processes explain the increase in the observed intensity of diurnal discharge fluctuations.