California is set to experience a significant shift in weather patterns this week as rain returns after a prolonged dry spell. With warm atmospheric rivers sliding down the Pacific Coast, Northern California can expect rain to end tule fog, though mountain snow is not anticipated in large amounts. A series of storms is forecasted, particularly impacting the Bay Area and Northern California, bringing heavy rain and potential flooding risks from December 20 to January 9. Meanwhile, Southern California may see wet weather return around Christmas Eve, coinciding with travel preparations for the holiday season. Residents are advised to stay alert for changing conditions, particularly as meteorologists anticipate a busy few weeks ahead due to increased atmospheric river activity linked to La Niña.