Warning Sirens
What Do They Mean and What Should You Do?
Outdoor warning sirens are designed to alert people who are outside of approaching danger. They are not intended to be heard indoors. Sirens are only one part of a three-part notification system, which also includes:
- NOAA Alert Radios
- Local news media (radio/TV)
How to Respond
When you hear the sirens:
- Go indoors immediately.
- Turn on a NOAA alert radio, TV, or trusted news source for official updates.
- Follow protective action instructions from emergency officials.
When Are Sirens Activated?
The South Holland Emergency Warning System sounds sirens when:
- A Tornado Warning is issued within 20 miles, or
- A funnel cloud has been sighted nearby
Activation Cycle:
- Sirens sound for 3 minutes
- Followed by 7 minutes of silence
- Cycle repeats until the warning is cancelled
Tornado Alerts Explained
- Tornado Warning: A tornado has been sighted or is imminent. Move to a safe place immediately.
- Tornado Watch: Conditions are favorable for tornadoes. Stay alert and be ready to take action.
Monthly Testing
- Sirens are tested on the first Tuesday of each month at 10:00 AM, weather permitting.
- Test lasts 30 seconds.
- Tests are cancelled during bad weather to avoid confusion.
NOAA Alert Radios
Because sirens are only for outdoors, a NOAA Alert Radio is essential indoors.
- Sounds a tone and announces the hazard and protective actions.
- New models are programmable by county and hazard type.
- Alerts include both weather and non-weather emergencies (for example, chemical spills).
Recommendation: If you don’t own one, invest in a NOAA Alert Radio. Choose a model you can program for your county and specific hazards.