Chicago, Illinois – Hot and humid conditions will grip northern Illinois through Monday as multiple rounds of thunderstorms threaten to interrupt outdoor plans, with some storms capable of producing damaging winds before cooler, less humid air arrives by midweek.
According to the National Weather Service in Chicago, one or two clusters of thunderstorms could move through the region beginning late tonight and continuing through Monday evening. While confidence remains low on exactly where storms will develop, any storm that forms could become severe, with damaging straight-line winds posing the primary hazard.
Temperatures today will climb into the upper 80s and lower 90s, with heat index values reaching 95 to 105 degrees, especially near and west of Interstate 39. Monday will be even more oppressive, with highs ranging from 85 to 93 degrees and heat index values climbing to 100 to 110 degrees, particularly if thunderstorms do not arrive early enough to limit daytime heating.
Communities including Chicago, Rockford, Joliet, Aurora, Elgin, Waukegan and surrounding areas should be prepared for rapidly changing weather conditions. The greatest chances for thunderstorms are expected from the early morning through midday Monday, with another increase in storm potential Monday evening.
Residents should stay hydrated, wear lightweight clothing and limit strenuous outdoor activities during the hottest part of the day. Anyone with outdoor plans should also monitor weather updates and have multiple ways to receive warnings, as storm coverage will be uneven and some locations could miss storms entirely while others experience severe weather.
Behind the storms, noticeably cooler and less humid air is expected Tuesday and Wednesday, with highs falling into the lower to middle 80s. Beachgoers should also be aware that dangerous swimming conditions are expected along southern Lake Michigan on Tuesday and Tuesday night, with an elevated swim risk continuing into Wednesday for parts of northwest Indiana.
Five-Day Forecast for Chicago, Illinois
- Sunday: High 86–91°, Low 71–77°. Very humid with a chance of thunderstorms late.
- Monday: High 85–93°, Low 68–74°. Breezy, very humid with thunderstorms possible morning through evening.
- Tuesday: High 80–86°, Low 61–68°. Cooler with lower humidity. High swim risk at Lake Michigan beaches.
- Wednesday: High 80–84°, Low 59–67°. Mostly sunny and comfortable. Elevated swim risk continues for northwest Indiana beaches.
