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Weather Information

Iowa lies in the humid continental zone and generally has hot summers, cold winters, and wet springs. At various times during the seasons, residents are challenged with severe weather. Storms and flash floods can occur in the spring and summer months, while winter can bring extreme cold and blizzard conditions.

Warning Sirens

Warning sirens are activated to alert residents who are outdoors that they should seek shelter during storm-like weather conditions. Warning sirens will be activated if a tornado has been sighted or may form near Johnston. A steady 3 minute tone will indicate a tornado warning and residents should immediately seek shelter . In addition, sirens will be sounded for a thunderstorm warning when winds reach speeds of up to 70 mph.

Frequently Asked Questions
Where can I go for more information?
Outdoor Warning Siren FAQ

Outdoor Siren Activation Guide

Outdoor Siren Quick Reference Guide

Polk County
NOAA All-Hazards Radio

 


 

 

 

 

 

The National Weather Service uses the term tornado watch to mean that conditions are such that a tornado is possible. Sirens are not sounded for a tornado watch.
The term tornado warning is used when formation of a tornado is imminent or has been reported.

Under the Polk County/Des Moines Metro Area outdoor warning system guidelines, sirens will be sounded for:

  • Tornadoes
  • Severe Thunderstorms with winds occurring/forecast to be 70 mph or greater (Effective with 2010)

Warning sirens are located at:

  • 70th Ave. and Beaver Dr.
  • 62nd and Pioneer
  • 93rd and Newgate
  • Beaver and 78th
  • Beaver and 73rd
  • 5700 Block of 54th Ct
  • Windsor 100' North of Oakridge Pl

If a warning siren is not operational contact Johnston Public Works, 278-0822