The observational record and a 1000-year climate modelling analysis provide further evidence of the impacts of Tropical Pacific interannual (ENSO) and Northern Pacific decadal-interdecadal (PDO or NPI) variability on the Pacific-North American (PNA) sector. Both the tropospheric circulation and the North American temperature suggest an enhanced PNA-like climate response and impacts on North America when ENSO and PDO variability are in phase. In association with the stationary wave anomalies, large stationary wave activity fluxes appear in the mid-high latitudes originating from the North Pacific and flowing downstream toward North America. There are significant Rossby wave source anomalies in the extratropical North Pacific and in the subtropical North Pacific. In addition, the axis of the Pacific storm track shifts southward with the positive PNA. Atmospheric heating anomalies of the same sign appear in both the Tropical Pacific and the North Pacific in association with this variability. Both sources of variability provide energy transports towards North America, which tends to favor the occurrence of stationary wave anomalies and would lead to a PNA-like wave anomaly structure.