Dense Fog Has Covered Northern Illinois
Widespread fog caused hazardous travel conditions for Monday morning commuters across the region.
Updated on Sept. 28, 2026 in Current Conditions
Dense, widespread fog blanketed parts of northern Illinois on Monday morning, significantly reducing visibility. The weather event impacted commuters traveling through areas northwest of Chicago.
Why it matters
Low-visibility conditions created hazardous travel environments, particularly near river valleys where fog lingered throughout the early morning hours.
Visibility dropped to a minimum of 0.25 miles across affected areas. The dense fog was concentrated east of Interstate 55 and south of Interstate 80.
The players
Northern Illinois
This is the primary geographic region affected by the widespread dense fog conditions.
Chicago
This major urban center served as the primary reference point for identifying the impacted areas northwest of the city.
The details
Fog conditions persisted throughout the morning, specifically impacting regions situated northwest of Chicago and near local river valleys. Officials noted that the thickest fog was localized to sectors defined by the I-55 and I-80 corridors.
Timeline
Monday morning, September 28, 2026, saw widespread fog emerge across northern Illinois.
The fog is expected to fully dissipate by 9 a.m. on September 28, 2026.
Seasonal Patterns
The current weather event follows a pattern set by the National Weather Service's dense fog advisory criteria for issuing travel alerts. Such conditions are typical for this region as cooling air settles over river valleys during the transition to autumn.
Drivers in northern Illinois should exercise extreme caution and maintain increased following distances until visibility improves. Residents navigating routes near I-55 and I-80 should allow for extra travel time while the fog persists.
The takeaway
Morning commuters should be prepared for sudden changes in road visibility when driving through river valleys or low-lying areas. Monitoring local weather updates remains the best way to avoid travel delays during sudden fog events.
Further reading
For more information on current atmospheric events in the region, visit the Current Conditions section.
