A dense fog advisory is in effect throughout the Chicago area Tuesday morning.
The advisory is in effect until noon and covers most of northern Illinois and parts of northwest Indiana, according to the National Weather Service. The fog advisory covers Cook, Will, Lake, DuPage, Kane, Kendall, LaSalle, Grundy, Winnebago, Boone, McHenry, Ogle, Lee and DeKalb counties in Illinois and Lake and Porter counties in Indiana.
The fog could reduce visibilities throughout the area to a quarter mile or less, the weather service said. Drivers are encouraged to slow down, use their headlights and leave plenty of distance ahead of them.