Fresno, California – A Dense Fog Advisory is in effect this morning across the heart of the San Joaquin Valley, creating potentially dangerous travel conditions for thousands of commuters. The National Weather Service (NWS) has warned that visibility may fall to one-quarter mile or less along major highways, especially during the early-morning rush.
Advisory covers major Central California counties
The alert remains active from late Monday night through late Tuesday morning, impacting Merced, Madera, Fresno, Tulare, and Kings counties. Communities such as Fresno, Merced, Visalia, Bakersfield, Hanford, Porterville, and Los Banos are all included in the advisory.
Forecasters say the dense fog will be at its worst during the morning commute, when saturated ground humidity and calm winds allow widespread tule fog to form across low-lying farmland and open stretches of highway.
Key travel corridors affected across the region
The NWS highlighted a long list of major roads where visibility is expected to drop rapidly, including:
- Interstate 5 (I-5)
- California State Route 99 (CA-99)
- Routes 33, 41, 43, 46, 59, 152, 165, 168, 180, and 198
These highways cut directly through areas prone to heavy winter fog. Drivers may encounter sudden whiteout-like conditions along both rural corridors and busy multi-lane sections.
What the National Weather Service says
Meteorologists at NWS Hanford explained that cool overnight temperatures, lingering moisture, and calm winds are creating the perfect conditions for dense tule fog formation. The agency noted that the fog could remain persistent until late morning, with only gradual improvement expected.
“Areas of dense fog will reduce visibility to a quarter mile or less across much of the San Joaquin Valley,” forecasters said in their early-morning update. “Motorists should be prepared for rapidly changing conditions.”
According to early NWS model projections, some pockets of fog could linger beyond the advisory period in low-lying or sheltered areas.
Why this fog event is especially concerning
Winter tule fog is one of the leading causes of serious traffic accidents in California’s agricultural regions. The low, thick fog can form without warning, creating situations where one stretch of road is clear and the next is nearly impossible to see.
Key risks include:
- Sudden visibility loss in seconds
- Multi-vehicle collisions on high-speed highways
- Difficulty spotting stopped vehicles or road hazards
- Hazardous merging and lane-change conditions
Travelers heading toward Fresno, Bakersfield, or Visalia during the early commute face the highest risk.
Safety tips for morning commuters
Officials urge drivers to take immediate precautions while traveling through the region. Recommended guidance includes:
- Use low-beam headlights rather than high beams, which reflect light back into the fog
- Reduce speed significantly and avoid sudden braking
- Allow extra distance between vehicles
- Follow road reflectors and lane markings carefully
- Avoid using cruise control in low-visibility conditions
- Leave early and give yourself additional travel time
The California Highway Patrol typically responds to more fog-related accidents during these winter advisory periods, so delays are possible throughout the morning.
Conditions expected to improve later in the day
Forecasters expect gradual clearing by late Tuesday morning as sunlight and shifting air help disperse fog layers. However, some areas—especially those near farmland and riverbeds—may see residual fog hanging on longer than expected.
For continuous updates, residents can check the National Weather Service Hanford feed, which provides real-time forecasts and alerts throughout the day.
Staying aware during fog season
Dense fog events are common in the San Joaquin Valley from December through February. With more fog expected in the coming weeks, officials encourage drivers to stay weather-aware and review safe-driving habits frequently.
If you live in the region and experienced visibility issues this morning, share your observations in the comments below.
