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Atmospheric rivers (ARs) are responsible for hazardous hydrometeorological events over western North America. For the period 2070-2099 relative to 1976-2005, regional climate model simulations driven by two coupled global climate models for the RCP4.5 and 8.5 scenarios project up to 90% increase in AR occurrences over western North America. Results also suggest that the increase in AR-related freezing rain (FR) events is possibly due to changes in both dynamical and thermal mechanisms associated with AR events. In the west coast of Canada, AR-related FR events are projected to intensify, which is facilitated by the increased midlevel ascent related to differential vorticity advection associated with ARs. The fraction of AR-related FR amount is projected to increase over the inland of western U.S. and the west coast of Canada, which is possibly driven by the increased temperature difference between the subfreezing near-surface layer and the above-freezing layer aloft.