Dec 31, 2022
An atmospheric river impacted the Bay Area on December 31st, resulting in significant rainfall across the San Francisco Bay Area. Initial forecasts called for the most intense rainband to progressively move south towards the Central Coast as the day went on. However, the morning of the 31st, a surface low developed west of San Francisco, and the river stalled over the Bay Area. This resulted in significant rainfall totals for many Bay Area sites. Most notably, downtown San Francisco received 5.4
Source: NOAA National Weather Service Storm Events Database (event 1079962). Narrative written by NWS staff at the time of the event.
This event is one of many recorded floods in San Mateo County. See the full FEMA flood zone map, NFIP claim totals, and disaster history for the area.