The National Weather Service issued a Severe Thunderstorm Warning for LaSalle County Wednesday evening, in effect until 9:15 p.m.
Area residents are warned of half-dollar size hail, cloud to ground lightning, and damage to vehicles in cities around Mendota, Earlville, and Troy Grove, according to the National Weather Service.
Residents are advised to take shelter and move away from windows, to an interior room on the lowest floor of a building.
The warning comes after dense fog blanketed the Chicago area early Wednesday, reducing visibility down to just hundreds of feet in some areas during the morning commute.
More than 90 flights were canceled at Chicago airports by 6 a.m. due to the low visibility that dropped down to a quarter of a mile or less at times.
Thunderstorms are expected to come to an end overnight, but occasional spotty showers or drizzle continue; otherwise mostly cloudy and mild as temps hold in the upper 50s to low 60s.
A Severe Thunderstorm Watch was issued for southern Illinois counties including Champaign that will remain in effect.
Thursday will be mostly cloudy with a few early morning showers, turning partly sunny, breezy and mild in the afternoon. Highs in the low to mid 70s.
A few late showers are possible Friday, but otherwise mostly cloudy, breezy and cooler. Highs in the low to mid 70s.
Looking ahead to the weekend, Saturday will be another mostly cloudy day but chilly in the morning, turning partly sunny; breezy and still quite cool in the afternoon with highs in the mid to upper 50s. Models show Sunday to be sunny and breezy but still cool for the season. A few showers possible in the evening. Highs in the upper 50s to low 60s.