Dense fog blankets much of the Bay Area Tuesday morning

The National Weather Service forecast in the greater San Francisco Bay Area on Tuesday morning called for patchy dense fog in the morning before skies gradually clear for sunshine.

Dense fog is being reported across the North Bay interior valleys and San Francisco Bay. Forecasters expect fog to spread south, impacting more of the bay shoreline and Santa Clara Valley by sunrise. The dense fog advisory expired at 11 a.m. Tuesday, but some parts of the region including the San Mateo Bridge and the Bay Bridge were still enshrouded in mist well after that.   

Reduced visibility down to a quarter mile was being reported in some areas, with SFO reporting visibility down to a 16th of a mile. As of 8:30 a.m., officials at the airport said 54 flights had been delayed due to foggy conditions.

The heavy fog was especially impacting drivers on Bay Area bridges, particularly the Bay Bridge, the San Mateo Bridge and the Golden Gate Bridge.

Drivers impacted by the fog are advised to make their vehicles visible to others both ahead of you and behind you by using their low-beam headlights or fog lights if available. Drivers should never use your high-beam lights.   

KPIX chief meteorologist Paul Heggen says tthe fog won't impact how much the region warms up, with highs  5°-10° above-average Tuesday, mostly mid to upper 60s with a few low 70s sprinkled in. Overnight lows are pegged to be in the 40s in the region, with some areas around the bay dropping into the 50s.

A weather system is on track to arrive early Wednesday morning, bringing rain to the region. Another batch of showers will follow that up on Thursday, with the total rainfall in the 0.10"-0.25" range, though a few spots in the North Bay could approach a half-inch.

The outlook is dry but cool Friday through the weekend, with near-normal highs in the 60s.

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• Dense Fog Advisory
• San Francisco