Tornado sirens blared across Downers Grove, Woodridge and Westmont around 3 a.m. Tuesday, Aug. 18, jolting thousands of residents awake. There was no tornado, no severe weather, no emergency of any kind.
A DU-COMM staff member accidentally triggered the outdoor warning sirens while conducting a planned system test, the agency said in a statement reported by NBC Chicago. The test was supposed to check the technology's functionality without actually activating the sirens.
Staff shut them off immediately.
DU-COMM apologized for the error, saying it regretted the unnecessary interruption and confusion the activation caused, according to CBS Chicago.
The Village of Downers Grove confirmed on X shortly after the activation that the siren was set off inadvertently and that there was no severe weather to be concerned about. That post drew more than 9,100 impressions. In a follow-up post, the village directed residents to DU-COMM's press release and noted that Downers Grove joined DU-COMM for 911 dispatch services in 2016 under Illinois law.
Residents from Villa Park to Wheaton also reported hearing the sirens, according to Fox 32 Chicago. The National Weather Service in Chicago confirmed nothing had been triggered from its office.
How the siren system works
DU-COMM (DuPage Public Safety Communications) manages outdoor warning sirens across DuPage County. In May 2025, the county upgraded to an automated system that activates sirens based on National Weather Service warnings without requiring a human to manually interpret a map and flip a switch.
DU-COMM Deputy Director Tyler Benjamin explained the change when the upgrade launched in May 2025: "Previously, it required someone to read a National Weather Service alert and interpret the area of the warning, and then manually activate the sirens based on the map."
Tuesday's accidental activation happened outside the normal test window. DU-COMM tests sirens on the first Tuesday of each month at 10 a.m., according to the Village of Westmont's emergency siren guidance.
What residents should know
DuPage County's outdoor sirens warn people who are outside. They should not be relied on as a primary notification indoors. When sirens sound during an actual emergency, residents should seek shelter and tune in to local news or weather radio for details.
The sirens do not use an "all clear" signal. If they sound a second time, it means a new warning has been issued or a more severe threat exists.
Coming up in the community
Thursday, Aug. 27: WSEC Cruisin' Nights car show, 5–9 p.m. on Cass Avenue in downtown Westmont. Hundreds of cars, live bands, vendors and kids' activities.
Saturday, Aug. 29: Electronics and More Recycling Event, 8 a.m. to noon at Westmont Village Hall, 31 W. Quincy St. Hosted by the Village of Westmont with eWorks, Inc. and DuPage County.
