St. Louis, Missouri – Drivers across Missouri and parts of west-central Illinois face a significant risk of dense fog overnight into early Monday, with visibility plunging to a quarter mile or less in some areas and hazardous travel expected through 9 a.m.
According to the National Weather Service in St. Louis, the thickest fog will develop in northeast and central Missouri, stretching into west-central Illinois. Conditions will be most dangerous along major routes including I-70, I-64, and I-55, where the fog is likely to be patchy but dense. The NWS urges motorists to use low beam headlights, slow down, and allow extra travel time for the Monday morning commute.
Cities like Columbia, Mexico, and Hannibal in Missouri, as well as Jerseyville and Carlinville in Illinois, are under the highest threat. Law enforcement and emergency responders are on alert for potential accidents due to rapidly changing visibility. While some rural areas may experience lighter fog, no region is immune, so caution is needed throughout the state.
Residents are advised to avoid unnecessary travel until fog lifts, keep headlights on low beam, and watch for sudden changes in road visibility. This weather pattern is common in mid-July but still poses a serious safety concern.
Fog is expected to gradually clear after 9 a.m., but additional advisories are possible if conditions persist into midday.
