Patches of Dense Fog Around Overnight and Into Thursday Morning... The combination of the warm temperatures, melted snow, and light rain has caused patches of dense fog to develop in a few spots across the area. While these patches are not widespread, locally visibility is down to a few hundred feet. If driving in dense fog, use low beam headlights, slow down, and leave plenty of distance between vehicles. The fog is expected to linger well into the morning hours of Thursday.