Outdoor / Severe Weather Warning Sirens

Outdoor Warning System

The Town of Flower Mound's Outdoor Warning System consists of twenty-nine (29) outdoor warning sirens located throughout the Town that are designed to inform residents who are outside of a possible emergency. The sirens may be activated in small groups for a localized emergency or they all may be activated simultaneously for a town-wide emergency. The Outdoor Warning Sirens are part of an emergency system designed to provide immediate and valuable information to citizens. The system is not intended to alert those who are within a home or other structure; however, it is possible that you may still be able to hear a siren while indoors depending on your proximity to a siren; taking into account outdoor conditions at the time of activation.

The Outdoor Warning Sirens should not be confused with the lightning detectors that are located at several Town parks as well as all LISD campuses. Additional information on the ThorGuard system may be found here.

What To Do If Sirens Are Activated

If you hear the sirens while you are outside, please go inside and seek shelter immediately and refer to a television or radio for further instructions. Please do not call 9-1-1 for severe weather information. Call 9-1-1 only to report life-threatening situations. To see siren locations, please refer to the map below.

6-14-22 web coverage map


The siren will produce a steady tone signal for three minutes. The sound will have a natural decrease / increase due to the rotation of the siren head. The sirens will only be initiated in the case of severe weather directly threatening Flower Mound as reported by the National Weather Service, a storm spotter, or certain Town employees that meets at least one of the following criteria:

  • Reported hail of 1.50” in diameter or greater (or smaller for areas or events where large numbers of people are outdoors)
  • Rotation in a dangerous cloud or a tornado
  • Straight-line winds over 70 mph

Siren Testing

The Outdoor Warning Sirens are silently tested every day to ensure that the system is functioning correctly. Audible tests of the system are performed on the first Wednesday of every month at 1 p.m., weather permitting.