Moisture from the rain combined with warm air Wednesday to create a dense fog throughout region, including in Butler County.
The fog continued into early Thursday, greeting many drivers with low-visibility conditions when they got in their vehicles to travel to work or school.
The fog was thick enough to prompt the National Weather Service to issue a Dense Fog Advisory for Butler and surrounding counties.
“Visibility is down to a quarter-of-a-mile or less at times,” according to the advisory. “Limited visibility makes travel very difficult.”
Forecasters expect the fog to burn off by 10 a.m. Thursday, leaving behind mild temperatures- a high near 60- and rain. Lots of rain.
New precipitation amounts between a quarter-to-a-half-inch is possible during the day, and then another three quarters-to-an-inch at night.
Isolated flooding is possible, according to the NWS.