SAN FRANCISCO (CBS SF) — A thick blanket of fog was draped over the San Francisco Bay Area early Thursday, triggering hazardous driving conditions from Cloverdale to the Golden Gate Bridge.

The National Weather Service issued a dense fog advisory from Sonoma County to San Rafael encompassing the entire morning commute until at least 9 a.m. Visibility was of a one-quarter mile or less.

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“If driving, slow down, use your headlights, and leave plenty of distance ahead of you,” forecasters said.

“Temperatures early this morning are running between 5-15 degrees commpared to 24 hours ago as sky conditions cleared out late Wednesday evening,” forecasters continued. “These conditions combined with residual low level moisture has allowed for patchy fog (dense at times) and low clouds to develop across the interior valleys as well as around the Monterey Bay.”

The fog was the final act of a weather front that left the season’s most significant rain totals around the San Francisco Bay Area over the last 36 hours.

According to the weather service, 4.48 inches of rain fell on Mt. Tamalpais, 3.16 inches in Ben Lomond, 1.68 inches on Mt. Diablo and 1.12 inches in Santa Rosa.