Areas of dense fog expected overnight into early Saturday morning... The combination of mostly clear skies, light winds, and cooling temperatures will favor fog formation late tonight into early Saturday morning. The densest fog will be most prevalent in deeper and more sheltered valleys and near bodies of water. Visibility could be reduced to a mile or less at times in some areas. Slow down, use low beam headlights, and leave plenty of space between you and the cars in front of you if driving in foggy conditions.