California ended 2022 with a heavy rainfall event that brought flooding to San Francisco and surrounding areas, resulting in landslides, inundated roads and evacuation orders. The second highest daily rainfall total on record fell on New Year’s Eve in downtown San Francisco (with records extending back to 1949), with 5.46in recorded. This is more than 25% of the annual average rainfall, and only 0.08in short of the all-time record set in November 1994.
Recent heavy rains have been part of an atmospheric river event – where a conveyor belt of warm, moist tropical air is able to interact with and feed into mid-latitude storm systems, greatly enhancing rainfall potential.
