Overview

• National Weather Service updated the dense fog warning at 11:58 p.m. Monday for St. Joseph, Branch and Hillsdale counties through 3 a.m. EDT Tuesday.
• Patchy dense fog formed rapidly overnight across northwest Ohio, northeast Indiana and adjacent Michigan counties, reducing visibility to a quarter mile or less.
• Earlier fog alerts in western and northwestern Pennsylvania expired or cleared after sunrise on Monday.
• Motorists are urged to reduce speed, maintain safe following distances and use low-beam headlights in near-zero visibility.
• Fog is expected to dissipate between sunrise and mid-morning, with visibility improving thereafter.