The advisory, which is in affect until 9 a.m., applies to parts of Alameda, Contra Costa, Marin, Monterey, Napa, San Francisco, San Mateo, Santa Clara, Santa Cruz, and Sonoma counties.
Coastal areas are expected to be most heavily impacted by the decrease in visibility, according to the weather service.
Motorists are advised to use caution as the rapid decrease in visibility can make driving difficult or even dangerous. The weather service recommends that drivers slow down and leave plenty of distance between cars while in motion.
The advisory means that visibilities will be reduced to less than one quarter mile along the San Francisco and Monterey bay coasts.