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 5.46 inches of rain on the 31st, the second wettest day on record. The Oakland Museum received its wettest day since records began in 1970, with 4.75 inches of rain.

Heavy Rain in ALAMEDA, CALIFORNIA
From 31-DEC-22 17:12:00 to 31-DEC-22 17:12:00 (PST-8)
Location: BERKELEY
Reported by: Trained Spotter

Trained spotter reported 4.45 inches of rain from 5 PM on December 30 to 5 PM on December 31.

Heavy Rain in SAN MATEO, CALIFORNIA
From 31-DEC-22 00:00:00 to 31-DEC-22 23:59:00 (PST-8)
Location: REDWOOD CITY
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Redwood City with 4.47.
12/31/2022 was the 3rd wettest in a record that goes back to 1906. The daily rainfall made up 42.8% of December 2022's rainfall.
The wettest day on record at Redwood City was back on 10/13/1962 with 4.88 inches.

Heavy Rain in SAN FRANCISCO, CALIFORNIA
From 31-DEC-22 00:00:00 to 31-DEC-22 23:59:00 (PST-8)
Location: SAN FRANCISCO
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

San Francisco Downtown site hit 5.46��� in the 24 hours of December 31st. This makes it the second wettest day on record, just 0.08��� less than 1st place (11/5/1994) with 5.54���
This also was 46.8% of the monthly rainfall (11.66���).

Heavy Rain in ALAMEDA, CALIFORNIA
From 31-DEC-22 00:00:00 to 31-DEC-22 23:59:00 (PST-8)
Location: ALAMEDA
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Oakland site had its wettest day on record (since 1970) with 4.75���, beating out the previous record set back on 1/4/1982 by just 0.01���
This day was 36% of December���s rainfall at this site.

Flood in SAN FRANCISCO, CALIFORNIA
From 31-DEC-22 14:30:00 to 31-DEC-22 14:30:00 (PST-8)
Location: OCEAN VIEW
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

CHP reported a car stuck in water, blocking the offramp from Southbound Interstate 280 to Monterey Boulevard.

Flood in SAN FRANCISCO, CALIFORNIA
From 31-DEC-22 12:54:00 to 31-DEC-22 12:54:00 (PST-8)
Location: SAN FRANCISCO
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

CHP reported flooding on the onramp from Bryant Ave to Southbound US Highway 101.

Flood in SAN FRANCISCO, CALIFORNIA
From 31-DEC-22 15:04:00 to 31-DEC-22 15:04:00 (PST-8)
Location: OCEAN VIEW
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

The onramp from San Bruno Avenue to Southbound US Highway 101 was flooded, and multiple vehicles were stuck.

Flood in SAN MATEO, CALIFORNIA
From 31-DEC-22 05:58:00 to 31-DEC-22 21:00:00 (PST-8)
Location: BAYSHORE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

CHP reported flash flooding of US Highway 101 at Oyster Point Road in South San Francisco at 5:58 AM. By 10:58 AM, the entire roadway had flooded and the highway was closed. The flooding caused traffic backups and diversions with Interstate 280 as the alternate. The northbound lanes were reopened around 8 PM and the southbound lanes around 9 PM.

Flood in ALAMEDA, CALIFORNIA
From 31-DEC-22 07:18:00 to 31-DEC-22 07:18:00 (PST-8)
Location: PIEDMONT
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

CHP reported flooding of the onramp from Northgate Avenue to California Highway 24.

Strong Wind in NORTHERN MONTEREY BAY, CALIFORNIA
From 31-DEC-22 13:30:00 to 31-DEC-22 13:30:00 (PST-8)
Magnitude: 22.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

A 120-foot tall cypress tree fell on a 72-year old resident of Santa Cruz within Lighthouse Field State Beach around 1:30 PM during a major rain event. Victim was pronounced dead at the scene despite attempts at medical care. At time of event, multiple reports of flooding, mudslides, and fallen trees were reported across the CWA, especially in low-lying and hilly areas.

Flood in SANTA CRUZ, CALIFORNIA
From 31-DEC-22 18:00:00 to 31-DEC-22 19:00:00 (PST-8)
Location: SOQUEL
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: County Official

The Old Mill Mobile Home Park in Soquel was evacuated, after several mobile homes flooded. KSBW television quoted a resident as saying that the river rushed in so fast that barely had time to leave the house. The resident compared it to ocean waves in their backyard. County officials also stated that they would later find debris in Soquel Creek that blocked the flow.

Flood in SAN FRANCISCO, CALIFORNIA
From 31-DEC-22 13:15:00 to 31-DEC-22 13:15:00 (PST-8)
Location: SAN FRANCISCO
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

The Montgomery BART station shut down the escalators and exits due to flooding.

Flood in SAN FRANCISCO, CALIFORNIA
From 31-DEC-22 10:36:00 to 31-DEC-22 10:36:00 (PST-8)
Location: OCEAN VIEW
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

CHP reported 2 feet of water flooding Southbound US Highway 101 near Silver Avenue.

Flood in SANTA CLARA, CALIFORNIA
From 31-DEC-22 00:00:00 to 31-DEC-22 23:59:00 (PST-8)
Location: WAYNE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Newspaper

A 56-year old man was found drowned in fast moving water on January 1 in Upper Penitencia Creek in San Jose after the creek overflowed the previous night.

Debris Flow in MONTEREY, CALIFORNIA
From 31-DEC-22 00:25:00 to 31-DEC-22 23:59:00 (PST-8)
Location: POSTS
Flood cause: Heavy Rain
Property damage: 0.01K
Crop damage: 0.00K
Reported by: Department of Highways

California Highway 1 was closed from Big Sur to Ragged Point due to rockslides across the highway in multiple places. As of April 2023, portions of the highway are still closed for repairs with no estimated time to reopen.