Outdoor Warning Siren Frequently Asked Questions (FAQ)
1. What do the guidelines say?
Under the Polk County/Des Moines Metro Area outdoor warning system guidelines, sirens will be
Severe Thunderstorms with winds occurring/forecast to be 70 mph or greater
The sirens may be sounded multiple times during the threat. There will be no “all clear” signal for the
2. What should I do when I hear the sirens?
Go inside to the lowest level, most-interior room of the structure and tune to NOAA All-Hazards Radio or
the local media for more detailed information on the storm’s location, timing, and intensity.
3. When are the sirens tested?
Sirens will be tested on the first Saturday of each month at noon. If actual severe weather threatens that
day, the test will be delayed until the next monthly scheduled test. A “growl” test may be conducted on
the third Saturday of the month. A “growl” test activates the system without a full audible alert of the
system. Sirens may not be tested from December through February when ice and cold temperatures may
damage the system.
4. Why can’t I hear the sirens in my house?
Sirens are an outdoor warning system designed only to alert those who are outside that something
dangerous is approaching.
5. Why don’t the outdoor warning sirens sound an all-clear signal?
People should be indoors and monitoring local media or NOAA All-Hazards Radio for updates on the
6. How often can I expect the sirens to sound for severe weather?
On average, the Polk County/Des Moines Metro Area experiences approximately 5-15 storms each year
that meet the siren guidelines.
7. Why were the guidelines developed?
When life-threatening weather is approaching, minutes or even seconds could make a difference. If
people are unsure or confused about an alert, they may not respond quickly or appropriately. By adopting
common outdoor warning system guidelines, confusion will be minimized, response time reduced, and
lives will be saved.
8. How were the guidelines developed?
Emergency management officials from Polk County working with area emergency dispatch centers as
well as law enforcement, fire departments, and other public safety officials developed the guidelines
together in cooperation with the National Weather Service. Input on the draft guidelines was also sought
from municipal and county officials from across the Polk County/Des Moines Metro Area. During the
fall of 2009, the final guidelines were shared with community governments for implementation.