Early morning commuters in the greater San Francisco Bay Area faced a challenging drive on Wednesday, with a Dense Fog Advisory in effect through 10 AM, according to the National Weather Service (NWS). Visibility was reduced to a quarter-mile or less, making the morning trek a crawl for many. The NWS urged drivers to exercise caution on area roadways amidst these conditions in an announcement made via their X account.
⚠Dense Fog Advisory extended to cover much of the greater SF Bay Area through 10 AM Wednesday. Dense fog 1/4 of a mile or less will be possible. Use caution driving on area roadways. #cawx pic.twitter.com/9X4Z0XDYxH
— NWS Bay Area 🌉 (@NWSBayArea) December 13, 2023
The fog is a result of stable atmospheric conditions and long nighttime hours, allowing the air to cool and saturate. While this is not a new phenomenon for the region, the dense fog had a strong foothold waiting for offshore winds to begin dispersing it. The thick fog shrouding the bay was accompanied by a dense fog advisory on the water until 8:00 a.m., the NWS reported from its Area Forecast Discussion. Simultaneously, the weather service issued a Freeze Warning for interior regions, including San Benito and Monterey Counties, where colder, clear skies led to sub-freezing temperatures until 9:00 a.m. on Wednesday.
Not just the roads, but the waters were also affected as visibility on the San Francisco Bay north of the Bay Bridge was diminished significantly. Mariners were advised to proceed with caution and use proper fog signals due to low visibility that would make navigation difficult, as detailed in a Marine Weather Message by the NWS.
In terms of impacts, the fog and freeze conditions could have detrimental effects on crops and sensitive vegetation and possibly damage unprotected outdoor plumbing, the NWS warned. These conditions are not only inconvenient, but they carry the weight of potential economic ramifications for those in the agricultural sector, particularly in the areas under the freeze warning. In addition to the fog and freeze, a Coastal Flood Advisory was in effect from 8:00 a.m. to 1:00 p.m. PST on Wednesday due to tidal levels running approximately 0.50–0.75 feet above predictions, the NWS stated in a Coastal Hazard Message.
