The National Weather Service in Des Moines has issued a dense fog advisory, which is in effect until 9 p.m. Wednesday evening.

Very low visibilities are expected, with some areas seeing near zero visibility. Conditions are expected to improve later as winds increase from the northwest and help lift the fog.

A dense fog advisory means visibilities will frequently be less than one quarter of a mile. The National Weather Service advises drivers to use headlights, slow down and leave plenty of distance ahead of you.