August 3, 2025 – With Tuesday’s monthly test at 10am of the tornado detection system, the city is reminding residents how Decatur’s tornado sirens work and what they mean.
The City of Decatur utilizes an automated outdoor tornado siren activation system. When activated, all outdoor warning/tornado sirens in Decatur go off at the same time. The system automatically activates when the National Weather Service (NWS) issues a tornado warning with a polygon that touches any part of Decatur’s geofence boundary. The geofence boundary is slightly outside City limits offering a safer coverage zone.
Outdoor warning sirens are intended to alert people who are outside to seek immediate shelter AND additional information. For complete weather awareness, all citizens are strongly encouraged to have a NOAA weather radio or a weather-alert app for timely indoor alerts and more detailed information on the weather warning.
Currently, this means that if a warning area intersects the geofence in northern Decatur/Macon County, all sirens in Decatur are activated. If you hear sirens, please seek additional information to be best informed about the weather warning.
You can sign up for Macon County’s Emergency Notification System: https://maconcounty.illinois.gov/emergency-alert-notification-system-macon-county-il/
