This study is concerned with the water cycle of the Mackenzie River Basin of northwestern Canada. The analysis of water vapour, clouds, precipitation, snow cover, discharge and temperature shows that the region is subject to substantial interannual variability and strong seasonal cycles. A number of processes unique to cold climate regions, such as the impacts of various precipitation types, affect the water cycle of the basin. As well, this basin is experiencing a strong warming trend that is linked with an enhancement of some water variables, and an apparent reduction in atmospheric recycling. The Mackenzie Basin also exhibits some overall characteristics which differ from other high latitude regions due to its unique geography.