The National Weather Service announced Wednesday that a heat advisory covering a broad swath of the Chicago metropolitan region has been extended and will conclude at 9 p.m. on September 2, 2026. The extension applies to counties that have been experiencing persistent hot and humid weather, prompting officials to maintain the warning for public safety.
The advisory now includes McHenry, Lake, Kane, DuPage, Cook, DeKalb, LaSalle, Kendall, Grundy, Will and Kankakee counties. Residents in these areas are urged to remain vigilant for heat‑related health risks as temperatures and moisture levels stay elevated. The advisory’s expiration time of 9 p.m. Wednesday marks the end of the formal warning period, though officials note that warm conditions may linger into the evening.
Heat advisories are issued by the National Weather Service when forecasted temperatures and humidity combine to create a heightened risk of heat exhaustion, heat stroke and other heat‑related illnesses. The agency’s criteria focus on both the absolute temperature and the heat index, which reflects how the body perceives temperature when moisture in the air is high. In the Chicago area, recent days have featured a steamy atmosphere that meets these thresholds, leading to the current advisory.
Authorities typically advise the public to stay hydrated, limit strenuous outdoor activity, and seek cooler indoor environments during peak heat periods. Vulnerable groups such as the elderly, young children, and those with chronic medical conditions are especially encouraged to take precautions. While the advisory will lapse at 9 p.m., residents are reminded that the risk does not vanish abruptly and that monitoring local forecasts remains important.
The extension underscores the ongoing impact of the summer heat wave that has affected the Midwest this week. As the advisory ends, the National Weather Service will continue to evaluate temperature trends and may issue further guidance if conditions warrant additional warnings.