Public safety and emergency management units of local government maintain a network of emergency warning sirens throughout the county. The systems are designed to alert individuals who are outdoors about severe weather emergencies such as tornadoes. The sirens are tested periodically according to the schedule below.

• Washtenaw County: tested at 12:00 Noon on the first Saturday of every month from March through September. During the test, the county's emergency operations center hosts a siren test net through the amateur radio N8DUY repeater starting at 11:30 a.m on 145.15 MHz. 
• City of Ann Arbor: tested every 2nd Tuesday of the month @ 1:00 p.m., with 1 minute of steady wailing from March through November. Please call the Office of Emergency Management at 734-794-6980 if you are *outdoors* and do not hear the sirens on the scheduled time and day of the testing.