The National Weather Service has issued a Dense Fog Advisory until 10 AM this morning for the Northern San Joaquin Valley, which includes the western, lower portions of Tuolumne and Calaveras Counties.
Specific locations also include Sacramento, Stockton and Modesto.
Dense fog can make driving very hazardous.
A Dense Fog Advisory means visibilities will frequently be reduced to less than one quarter mile. If driving, slow down, use your low beam headlights and leave plenty of distance ahead of you.