Chicago, Ill. – Northern Illinois is set for several more days of comfortable summer weather before a sharp warmup sends temperatures into the 90s and pushes heat index values above 100 degrees early next week.
According to the National Weather Service in Chicago, highs will remain seasonable through the end of the workweek, reaching 75 to 79 degrees Thursday, 77 to 82 degrees Friday, and 80 to 85 degrees Saturday under mostly sunny to partly cloudy skies. Overnight lows will gradually warm from the upper 50s and lower 60s into the upper 60s and lower 70s by the second half of the weekend.
The warming trend accelerates Sunday, with afternoon highs climbing into the upper 80s to lower 90s. A 20% chance of a few late-day showers and thunderstorms could develop, but many locations will remain dry through much of the day.
Monday is expected to be the hottest day of the stretch, with highs reaching 90 to 94 degrees across much of northern Illinois. Combined with increasing humidity, heat index values near or above 100 degrees are likely, creating hazardous conditions for anyone spending extended time outdoors. There is also a 20% to 30% chance of showers and thunderstorms Monday as the hotter, more humid air settles over the region.
Residents should begin preparing now for the return of dangerous heat by staying hydrated, limiting strenuous outdoor activities during the afternoon and checking on older adults, children and others who are especially vulnerable to high temperatures. Never leave children or pets unattended inside parked vehicles.
Five-Day Forecast for Chicago, Illinois
- Thursday: High 75–79°, sunny and comfortable.
- Friday: High 77–82°, partly sunny.
- Saturday: High 80–85°, warmer with increasing humidity.
- Sunday: High 88–93°, slight chance of late-day thunderstorms.
- Monday: High 90–94°, hot with heat index values above 100° and a chance of thunderstorms.
