Temperature and precipitation trends have been observed to change over the last several decades in northwestern Canada. Within theYukon Territory winter temperatures have increased in all regions, while summer temperatures have increased in all regions except southern Yukon. Summer precipitation has been observed to increase in all regions, while winter precipitation has decreased in most regions with the exception of northern and central Yukon.

Hydrologic response was generally found to be characterized with higher year round flows. Significant changes were observed in mean annual flood (MAF) over the last 20 years, with a progressive decrease in this parameter moving from south to north, presumably due to increased pathways to the stream channel as a result of degrading permafrost. The greatest increases in MAF were observed to occur from predominantly glacerized systems in southwestern Yukon. Mountainous streams were found to have the timing of the freshet advanced. Changes to summer flows are variable, with increased flows in northern regions and decreased flow rates in southern regions.

Apparent changes to winter baseflow conditions over the last two decades are most significant. The greatest observed increases in this parameter have occurred in northern regions of continuous permafrost, with a less frequent observed increase moving southward to regions of discontinuous and sporadic permafrost. These observed changes are likely due to degrading permafrost allowing greater groundwater contributions to winter baseflow.

Significant changes to Yukon ice regimes are also apparent. Break-up timing has been observed to advance the frequency of winter, and early spring break-up events have increased, with likewise an increased severity of spring break-up flooding.

Because of the apparent changes in hydrologic trends, adaptations to Yukon water management strategies are required.