A Dense fog advisory has been issued until 9am this morning for the following counties, Benton, Buchanan, Cedar, Clinton, Delaware, Des Moines, Dubuque, Henry, Iowa, Jackson, Jefferson, Johnson, Jones, Keokuk, Lee, Linn, Louisa, Muscatine, Scott, Van Buren, Washington, Kossuth, Winnebago, Worth, Hancock, Cerro Gordo, Humboldt, Wright, Franklin, Butler, Bremer, Webster, Hamilton, Hardin, Grundy, Black Hawk, Greene, Boone, Story, Marshall, Tama, Guthrie, Dallas, Polk, Jasper, Poweshiek, Adair, Madison, Warren, Marion, Mahaska, Adams, Union, Clarke, Lucas, Monroe, Wapello, Taylor, Ringgold, Decatur, Wayne, Appanoose and Davis.

Visibilities will drop to under a quarter of a mile in these locations. This may also create a thin coating of ice on exposed surfaces, especially bridges and overpasses. The fog will begin to burn off by the mid-morning hours as southerly winds begin to increase.