Pacific salmon (Oncorhynchus spp.) are anadromous fish distributed around the Pacific Ocean. Pacific salmon generate numerous ecosystem services related to the nutrition, livelihoods and culture of humans. Widespread declines in this vital resource over the past century and specifically the last few decades have prompted efforts to identify the drivers of and remedy Pacific salmon decline. I used quasi-Poisson Generalized Linear Models (GLMs) to quantify the influence of multiple environmental and anthropogenic factors on the run size of Yukon River Chinook Salmon (Oncorhynchus tshawytscha) that spawn upstream of Whitehorse, Yukon, Canada. The main predictor of population variation was sea surface temperature, discernable during both marine entry and exit. Whitehorse Chinook Salmon are a small, edge population and my findings suggest that they may experience exacerbated effects of future perturbations to North Pacific and global climate compared to other populations of the same species.