The City of Chicago's Emergency Warning System (EWS) is an outdoor, all-hazards siren system that is used to warn the general population of a potential danger in a short amount of time and to notify them that the emergency has passed.
Chicago currently has 112 sirens located strategically on poles 1 to 2 miles apart throughout the City to ensure total citywide coverage. EWS may be activated by individual siren, by siren zone (there are 12 siren zones in Chicago), or citywide.
What Do the Sirens Mean?
The system uses two siren tones only. When they are activated during an emergency, the sirens will be activated for 3 minutes.
Please note that the City does perform a monthly siren test to ensure all sirens are functioning. The entire system is tested for 30 seconds at 10:00am on the first Tuesday of every month.
What Should I Do if I Hear the Sirens?
If the sirens are activated - and it is not our monthly 30-second siren test - the public should see it as a signal to:
When a Tornado Watch is issued by the National Weather Service, tornados are possible in our area. Remain alert for approaching storms.
When a Tornado Warning is issued by the National Weather Service, it means that a tornado has been spotted or indicated by weather