San Diego, CA – The National Weather Service (NWS) in San Diego has issued a Dense Fog Advisory for coastal areas of San Diego and Orange Counties, warning of visibility falling below one-quarter mile through 6 a.m. PDT Wednesday, October 29. Drivers and early commuters are urged to exercise extreme caution as thick fog blankets much of Southern California’s coastal corridor.
The Weather Alert: Dense Fog Advisory in Effect
According to the National Weather Service, the advisory covers key areas along Interstate 5, Highway 1 (Pacific Coast Highway), and nearby routes through Oceanside, Huntington Beach, San Diego, Chula Vista, and Costa Mesa.
Forecasters say dense fog will persist through the early morning hours, reducing visibility to less than one-quarter mile in many locations. The advisory remains active until 6 a.m. Wednesday, with the potential for localized patches of even lower visibility near the coastline.
“Visibility may drop suddenly and unpredictably across coastal highways and intersections,” forecasters said in a statement.
Travel Impact and Safety Precautions
The NWS has cautioned that these fog conditions could make driving particularly hazardous, especially for those commuting before sunrise. Reduced visibility increases the risk of accidents, especially on high-speed roads and near coastal lowlands where fog tends to thicken.
Authorities are reminding motorists to follow key safety tips for driving in foggy conditions:
- Reduce speed and maintain extra distance between vehicles.
- Use low-beam headlights or fog lights instead of high beams.
- Avoid sudden lane changes or braking when visibility is poor.
- Be especially cautious at crosswalks and intersections, where pedestrians may be difficult to see.
Transportation officials are also advising commercial truck and delivery drivers to allow additional travel time and avoid unnecessary trips during the advisory period.
Meteorological Explanation: Why Coastal Fog Forms
Meteorologists attribute the dense fog to cool, moist air trapped near the ocean surface under a marine inversion layer. When coastal temperatures drop overnight, warm air above prevents the cooler, moisture-laden air from rising, creating a thick fog bank that lingers until sunrise.
This phenomenon is common during autumn mornings in Southern California, especially when light winds fail to disperse the marine layer. As temperatures rise after sunrise, the fog is expected to gradually lift, improving visibility by mid-morning.
Expected Duration and Outlook
According to the NWS forecast, the fog will begin to thin between 6 and 8 a.m., with full visibility expected by 9 a.m. on Wednesday. However, patchy fog may return overnight into Thursday morning as the marine layer redevelops along the coast.
Drivers planning early departures are encouraged to check real-time traffic and weather updates before heading out. The NWS also recommends monitoring local radio and digital weather channels for any extensions or updates to the advisory.
Community Impact and Public Advisory
Public safety officials in San Diego and Orange Counties are urging residents to remain alert, especially near coastal interstates and low-lying valleys where fog tends to accumulate. Commuters using Interstate 5, Highway 78, and Highway 1 should prepare for sudden drops in visibility and drive with extreme caution.
Air travelers may also experience minor delays at coastal airports, including San Diego International (SAN) and John Wayne Airport (SNA), due to reduced runway visibility during the early morning hours.
Conclusion
The Dense Fog Advisory for Southern California’s coastal areas serves as a timely reminder of how quickly weather conditions can change. With visibility reduced to less than a quarter mile, the National Weather Service urges all drivers to slow down, stay alert, and use headlights wisely until the fog lifts later Wednesday morning.
What are your thoughts on the foggy conditions in SoCal? Share your experiences and safety tips in the comments below.
