North Bay Interior Valleys under Dense Fog Advisory Until Friday Morning
On Friday, the National Weather Service (NWS) San Francisco CA issued a dense fog advisory effective until 10 a.m. for the North Bay Interior Valleys.
Fog Conditions and Visibility
The NWS warns of visibility expected to be one quarter mile or less due to dense fog.
"Visibility one quarter mile or less in dense fog."
Driving Safety Advisory
Low visibility may create hazardous driving conditions. The NWS advises drivers to:
- Slow down
- Use headlights
- Maintain plenty of distance from vehicles ahead
"Low visibility could make driving conditions hazardous," says the NWS. "If driving, slow down, use your headlights, and leave plenty of distance ahead of you."
What a Dense Fog Advisory Means
A dense fog advisory is issued when widespread dense fog develops, causing visibilities to frequently drop to one-quarter of a mile or less. These conditions make travel dangerous, so caution is strongly advised, or driving should be avoided if possible.
Fog Driving Safety Tips
- Drive slowly and carefully
- Use headlights, not high beams
- Keep a significant distance from other vehicles
- Avoid driving if you can during dense fog
Source: The National Weather Service
This story was originally published November 7, 2025 at 1:52 AM.
Author’s note: Dense fog advisories highlight the importance of cautious driving to prevent accidents and ensure safety in low-visibility conditions.