The City of Lewisville Outdoor Warning System was developed to alert and notify citizens in outdoor areas of emergency situations. The intended response to activation of the Outdoor Warning System is for residents to go indoors and seek further information from the various sources available to them.
 
The sirens may be activated for a number of reasons, including (but not limited to):

• The National Weather Service issues a severe thunderstorm warning is issued with the phrase, “destructive winds in excess of 70 mph (or higher) are likely with this storm; and/or
• Destructive hail, 1.5” or larger is likely; and/or
• The National Weather Service issues a Tornado Warning for Denton County that MAY impact the City of Lewisville; and/or
• Tornadic activity has been reported by a reliable source in Denton County or approaching Denton County; and/or
• Hazardous Chemical Emergency; and/or
• Other emergencies, as deemed necessary by the Emergency Management Coordinator, on-duty Battalion Chief, Chief Officer, City Manager’s Office or other authorized personnel.

The outdoor warning siren system is tested on the first Wednesday or each month at 1 p.m. for 90 seconds, weather permitting. During real emergencies, the system is activated for a full 3 - minutes and may be activated multiple times.

This map below shows the status of each siren. To view the current status and comments for a specific siren click in the blue circle around the siren location.  If the marker is green the siren is in working order.  If the marker is yellow the siren is currently down.

Three types of sirens are part of the system: Whelen Vortex R4 rotating, Whelen WPS 2810 Omni-Directional, and Whelen WPS 2906 Omni-Directional.