Outdoor Warning System

The City of Duncan maintains and operates an outdoor warning system designed to alert people who are outdoors during emergencies.  This system is composed of 28 sirens which provide excellent coverage throughout our city.  

The Outdoor Warning Siren System is now modified and configured for automatic activation in the event a Tornado Warning is issued by the National Weather Service.  The siren system now monitors the National Weather Service’s Emergency Alert System for Tornado Warning information. When a warning is populated on the weather map and a red TOW (Tornado Warning) polygon appears, the sirens will automatically activate if the red TOW polygon intersects with our Outdoor Warning Siren coverage area. 

This modification includes all four City of Duncan lakes- Lake Fuqua, Lake Humphrey, Duncan Lake and Clear Creek Lake. Additionally, the lakes are now independent of each other for siren activation. Previously, all lake sirens had to be activated for a warning at any of the lakes. Now, each lake is independent, and a siren can be sounded individually or in a group of affected lakes. 

Siren Activation

In order for sirens to be activated, it must meet one of the following three criteria:

  • Tornado warning issued by the National Weather Service that could effect any part of the city limits of Duncan
  • Confirmed sighting of a tornado by a trained weather spotter
  • If winds are going exceed 65 mph


Weekly testing of the siren system is now fully automated unless severe weather is in the area or forecast.  Each lake siren is automatically activated sequentially at 11:59 AM every Monday.  The City of Duncan sirens will follow at noon.  The computer runs the testing sequence for four minutes and tests multiple functions such as a Wail for Tornado Warning, Steady for All Clear, and monitors siren voltage and current, battery levels, rotation, charger status, line voltage and communications strength. These conditions are communicated back to the central activation point and relayed to city staff if any maintenance is needed. 

Future Improvements

Future Improvements planned will integrate automated Lightning Detection and Lightning Warning in City of Duncan parks, walking trails, lakes, and Abe Raizen Sports Complex. These lightning warning devices will be voice capable sirens that will give a voice warning of approaching lightning and instruct users to take shelter.  Two of these sirens will be located at the Hillcrest and Douglass splash pads and will deactivate the water pumping system during the warning condition to encourage users to leave and take shelter. The sirens will also be able to sound voice announcements for Tornado Warnings, Flood Warnings, High Winds, Siren testing and more. The sirens, to be located near Halliburton Stadium, Fuqua pool, all parks, splash pads, and sports complex will be capable of Public Address and will be used to broadcast messages during events such as Fourth of July for lost children, emergencies, or any other need that may arise. 

We are excited about these improvements, and improvements to come, and believe they will make the Outdoor Warning Siren System more reliable, more functional, and give the public more time to reach shelter in the event of an emergency.  


The siren system is designed to be an outdoor warning system. Newer construction homes are typically built to suppress outside traffic and neighbor noises, unfortunately the sirens are suppressed as well.  There are many other means of warning for those indoors. These include local television, AM/FM radio, National Oceanic and Atmospheric Administration (NOAA) all-hazards radios (weather radio), social media, telephone apps and the City of Duncan’s Smart 911 Alert system. You should make sure you have several sources of weather warning information.  

When the sirens sound during severe weather, take cover immediately. If you wish to seek additional information, do that after you are in your shelter.  Do not go outside or look out the windows as these are dangerous places during severe weather.  Never call 911 unless there is a true emergency to report.