Dense Fog in Hardin, Illinois

The long duration fog event continued from the late afternoon of the 24th through the morning of the 25th. Dense fog formation of a quarter mile or less was most widespread in Southern Illinois during the evening on the 24th through the morning on the 25th. Calm winds, light drizzle, and dew points in the lower 50s over a rapidly diminishing soil frost depth contributed to fog formation. This fog event had the largest coverage area in over a decade, with Dense Fog Advisories stretching from PA to ND to TX to portions of the FL Panhandle.