Outdoor warning sirens begin monthly testing; First test on Monday, April 6 at 10 a.m.Please be aware that there will be an audible test of the outdoor emergency sirens in Louisville this Monday, April 6, at 10 a.m. From the Boulder County Sheriff's Office: Outdoor emergency sirens in several Boulder County communities will begin a new year-round monthly testing schedule as part of ongoing emergency preparedness efforts. Moving forward, sirens will be tested at 10 a.m. on the first Monday of each month, year-round. The first audible test under the updated schedule will occur on Monday, April 6, 2026. There will be no evening test as in previous years. During these tests, the community will hear a voice announcement indicating a test, followed by a one-minute siren activation. Outdoor warning sirens that are part of this new testing schedule are in Eldorado Springs, Erie, Jamestown, Lafayette, Louisville, Lyons, and Marshall. This updated, year-round testing schedule helps ensure the siren system remains operational and reliable, while also extending power supply battery life. Regular audible testing also supports preparedness efforts by maintaining community awareness and familiarity with the warning system. These sirens are designed to alert people who are outdoors to potential emergencies, including severe weather, hazardous materials incidents, and wildfires. Sirens are not intended to be heard indoors. In addition to the monthly audible tests, the siren system is silently tested daily at 8 a.m. to monitor functionality. If severe weather or a significant emergency occurs during a scheduled test, the audible test may be canceled. The monthly siren tests serve as an important reminder for community members to sign up for emergency alerts at BOCOAlert.org, which provides notifications via phone, text, and email. Community members are also encouraged to review their personal emergency plans and be prepared to respond to hazards such as flash floods or other emergencies. For more information about preparedness and training opportunities, visit BoulderODM.gov. | 
