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Outdoor Warning Siren Changes - New Test Time and Type of Warning

September 28, 2021
Beginning Nov. 1, 2021, outdoor warning sirens in St. Peters will be tested at a different time. The sirens will sound at 11 a.m. on the first Monday of each month rather than 9 a.m. This change will allow our Outdoor Warning System test to coincide with other area agencies. St. Charles County recently moved its test to 11 a.m. to coincide with St. Louis County siren tests.

Another change, effective immediately, is that the outdoor warning sirens in St. Peters will activate during Destructive Severe Thunderstorm Warnings in addition to Tornado Warnings. Destructive Severe Thunderstorm Warnings are when weather conditions are expected to cause 2.75-inch hail (baseball-sized or larger) and/or 80 mph thunderstorm winds.

The City of St. Peters is adding Destructive Severe Thunderstorm Warnings to its Outdoor Warning System at the recommendation of the National Weather Service. All cell phones also will activate during Destructive Severe Thunderstorm Warnings.

St. Peters’ Office of Emergency Management tests and operates 14 outdoor warning sirens as part of the City’s Outdoor Warning System. The sirens are spaced to provide warning for individuals who are outdoors. When sounded, you should take cover in your home's basement or the most secure room you can find in the center of your home or any other building you might be in.

How many more times can you expect to hear outdoor warning sirens as a result of this change? The National Weather Service says that St. Charles County has had seven Destructive Severe Thunderstorm Warnings since 2012—an average of less than one warning per year. The City of St. Louis has had one of these types of warnings and St. Louis County has had four since 2012.

However, the National Weather Service has found that Destructive Severe Thunderstorm Warnings are unlikely to be false warnings when compared to Tornado Warnings. Since 2012, of the 54 Tornado Warnings combined in St. Charles County, City of St. Louis and St. Louis County, more than half (30) have been false alarms. Meanwhile, all 12 Destructive Severe Thunderstorm Warnings during that time were verified.