Parts of northern California could see up to a foot of rain, but Phoenix will remain dry and warmer than usual.

Heavy precipitation is falling mostly in mountain areas. A flood watch in also in effect for the coast of central California, including the San Francisco Bay Area and Sacramento Valley.

Cooler, cloudier conditions and periods of light rain are forecast in San Diego County through Friday night as a weakening atmospheric river moves southward into Southern California, according to the National Weather Service.