Dense Fog Advisory For San Joaquin Valley In California, US: What Tourists Need To Know!

Published on November 25, 2025

The Central California San Joaquin Valley, the heart of the region, is experiencing a situation where people visiting and living there are literally waking with very limited visibility as a dense fog advisory issued by the National Weather Service (NWS) Hanford office becomes effective. The advisory was published at 1:35 PM PST on the 24th of November and it encompasses the whole valley area, still being valid until Thursday 27th of November at 1:00 PM PST.

Fog alert details

According to the official NWS statement, visibility is expected to drop to one‑quarter of a mile or less. The advisory applies to the San Joaquin Valley portion of Central California. The timeframe is from midnight until 12 noon each day from Tuesday through Thursday. Major highways affected include:

• Interstate 5
• California State Routes 99, 33, 41, 43, 46, 59, 152, 165, 168, 180 and 198
  The advisory warns of hazardous driving conditions due to low visibility.

Why the fog is forming

Meteorologists from NWS Hanford explain that a ridge of high pressure has stabilized the atmosphere across the valley, promoting radiative cooling at night and allowing thick fog to form each morning. The low‑lying valley and calm winds further enhance the effect. The discussion notes repeated chances of fog each morning through the week.

Tourist destinations impacted

With the valley’s visibility drastically reduced, several popular sites are likely to be affected:

• Lodi, California wine country – famous for vineyards and wine‑tasting experiences.
• Agritourism farms in the San Joaquin Valley offering pick‑your‑own produce and tours.
• General drive‑through scenic routes across the region whose vistas may be obscured.

Travellers planning to visit these destinations should factor in slower travel times, potential delays, and limited views until midday when the fog tends to lift.

Safety protocols for visitors and drivers

For those on the road, the NWS advises:

• Slow down and drive below normal speed.
• Use headlights (low beam) — do not rely on high beams in dense fog.
• Increase the distance between your vehicle and the one ahead.
• If visibility becomes extremely poor, consider pulling off the highway safely until conditions improve.
• Avoid sudden lane changes or overtaking in heavy fog patches.
• For tourists unfamiliar with the terrain: allow extra time, avoid travelling during the midnight‑to‑noon window if possible, and check with local travel advisories or your accommodation for updates.
• Use navigation devices and be extra attentive to highway‑exit signage, as fog can obscure these.
• If you walk or cycle, wear visible clothing and avoid roadside travel during the fog window.

What it means for travel plans?

For you, as a travel journalist, this advisory means a few specific implications: tour‑bus schedules and vineyard tastings may run late, guided farm visits might begin after fog‑lifting midday, and photo‑opportunities in the valley may be restricted until visibility returns. Many destinations may ask visitors to wait or adjust arrival times. Hotels and tour operators in the valley could be advising travellers accordingly.

In the final analysis, while the San Joaquin Valley will clear as the day progresses, the early‑morning hours pose significant hazards for those behind the wheel or moving between destinations. So, whether you’re planning to stop at a vineyard in Lodi, explore agritourism farms, or drive across the valley, applying the safety protocols listed can make the difference between a smooth journey and a risky one.