Hanford, California – Drivers across California’s central San Joaquin Valley could face hazardous travel conditions early Tuesday as dense fog sharply reduces visibility during the morning commute, creating a high transportation risk across several major roadways.
According to the National Weather Service in Hanford, a Dense Fog Advisory is in effect from around 3 a.m. until 10 a.m. Tuesday for much of the San Joaquin Valley. Widespread visibility below one-quarter mile is expected, with some locations seeing visibility drop under 200 feet, especially in low-lying and rural areas.
The fog is expected to impact cities including Hanford, Visalia, Fresno, Bakersfield, and surrounding communities. Major travel corridors such as Highway 99, Interstate 5, and State Route 180 are at risk for sudden visibility drops, particularly before sunrise. Drivers may encounter rapidly changing conditions, with dense fog pockets developing with little warning.
Temperatures overnight will remain mild for January, generally in the upper 30s to lower 40s, preventing frost but allowing fog to thicken and linger through mid-morning. Daytime highs Tuesday are expected to climb into the mid to upper 50s once fog lifts.
Transportation officials warn that dense fog significantly increases the risk of chain-reaction crashes, especially during peak commute hours. Motorists are urged to slow down, use low-beam headlights, and maintain extra distance between vehicles. High-beam headlights can worsen visibility by reflecting light back into the fog.
The National Weather Service’s experimental Fog Severity Index places much of the valley in a high-risk category, signaling the potential for travel disruptions and delayed commutes. Officials also recommend considering delaying non-essential travel until conditions improve later in the morning.
Fog is expected to gradually lift after 9 or 10 a.m. as daytime heating improves visibility, though some areas may remain hazy into late morning. Additional fog advisories are possible later this week if stagnant air conditions persist across the valley.
