Upwelling in eastern boundary current regions is crucial to bringing nutrient-rich water to the photic zone and supporting the associated ecosystems. This upwelling is a result of the wind-driven ocean circulation and is therefore susceptible to changes in the atmospheric circulation. We use the Community Earth System Model and observational data to explore the response of upwelling in the California Current and Canary Current systems to shifts in the Northern Hemisphere subtropical high-pressure systems. We find that shifts in the North Pacific subtropical high explain a substantial fraction of both the short-term variability and projected trend in upwelling in the California Current system during boreal summer. By contrast, the Canary Current system is less affected by shifts of the North Atlantic subtropical high, mostly because the strongest wind anomalies associated with shifts of this high-pressure system occur too far north. We also find little impact from the Northern Hemisphere Hadley cell.