Washtenaw County Outdoor Warning Siren System

The Washtenaw County Sheriff Emergency Services Division is responsible for the activation of eighty nine designated outdoor warning sirens throughout Washtenaw County. These sirens are triggered when appropriate by Washtenaw County, but they are maintained by local governments under vendor service agreements.

Purposes for Activation

Except for scheduled testing, these sirens will be activated when:

  • The National Weather Service has issued a tornado warning
  • A severe thunderstorm has been detected with 75 MPH winds or greater
  • A hazardous materials accident or other local emergency requires immediate protective action by the public
  • An attack on the United States is imminent, underway or has recently occurred

Coordination with the Emergency Alert System

Except for routine siren tests, official Emergency Alert System messages will be generated by the Emergency Services Division, National Weather Service, or other authorized state or federal agency, and disseminated to the electronic media each time the sirens are activated (see Recommended Public Response).

Recommended Public Response

Activated sirens are an indication that members of the public should immediately go indoors and listen to local Emergency Alert System radio stations for official information. Washtenaw County’s emergency stations are:

  • WEMU 89.1 FM (LP-1)
  • WWWW 102.9 FM (LP-2)

Routine Testing

All Washtenaw County operated sirens will be tested at noon on the first Saturday of every month from March through October. If severe weather is possible on the afternoon of a test, it will be delayed until the following month.

Outdoor Warning Siren Coverage Map