Alerts, Notifications, and Warnings

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Denver's Emergency Alerting Systems

Denver has two ways of directly notifying residents and visitors about emergencies as they happen and what actions people should take to remain safe. Our Reverse Emergency Notifications require people to sign up while our Wireless Emergency Alerts do not. Click on the tabs to learn more about each alert and how you can ensure you're able to receive vital information during emergencies and disasters. 

Reverse Emergency Notifications (REN)

Reverse Emergency Notifications (REN) 

Denver's Reverse Emergency Notifications (REN alerts) send an alert to the public via voice call, text message or email when there is police activity in their designated areas. The alerts provide direction and information on how the public can remain safe during an incident. Residents can sign up to receive alerts by providing your contact and location information, while also requesting alerts for multiple locations. If you move, you can update your location and contact information using the the alert management dashboard. You can also can opt out of the notifications by pressing '0' during a voice call or replying “STOP”, via text message. 

Sign Up to Receive Reverse Emergency Notifications

Wireless Emergency Alerts (WEA)

Wireless Emergency Alerts (WEA) 

Denver has used Wireless Emergency Alerts to keep the community informed since 2013. When there is an emergency relevant to your location, you will receive an alert on your phone, similar to an Amber Alert with guidance on what to do to remain safe. You do not need to sign up to receive these alerts, however, you can click here(PDF, 216KB) to ensure your alerts are ON and WORKING. 

Smart911 Alerts (ADA Accommodations)

During emergencies, do you have a disability-related accommodation or assistance need? If so, Denver's Smart-911 system allows you to input your needs and it is automatically shared with first responders in emergencies!

Sign up for Smart911

Additional Information about Denver's Alerting Capabilities

Denver has has the ability to notify residents and visitors of emergencies as they happen while also providing guidance on how people can remain safe through an incident. Click the tabs to learn more about our alerting capabilities. 

All-Hazard Sirens

The City and County of Denver’s Outdoor Warning Siren System was installed between 2012 and 2014. There are 86 sirens citywide: 75 in the city and 11 at Denver International Airport (DEN). Up until 2023, the sirens were primarily used for tornado warnings, however, following recent local and national disasters, the city updated it's policy to allow the city to activate their sirens for any imminent or widespread emergency including, but not limited to events such as tornadoes, dam failure resulting in dangerous flooding, wildfires, and hazmat situations. 

When sirens are sounded, people are encouraged to take shelter immediately and tune into their phones, computers, and local media for subsequent alert and warnings and further instructions on how to remain safe and protected. Sirens do not send an “all clear” message. If sirens continue to sound, people need to continue to be follow prescribed recommended action(s) to remain safe. 

When you hear a siren in Denver, you're encouraged to: 

  • Seek shelter indoors, immediately and close your homes windows and doors. 
  • Once you are inside a secure location, tune to local media (TV, radio, social media, mobile device) or NOAA weather alert radio to inform yourself of the emergency and hear what you need to do to remain safe. 
  • Follow all guidance and recommendations issued to, they could save your life. 

In addition to our alerting technology, we encourage members of the public to follow our social media at and (formerly Twitter) to receive important information, including life-safety guidance during emergencies and disasters. 

Emergency Alert System (EAS Alerts)

The Emergency Alert System (EAS) is a national public warning system that requires radio and TV broadcasters, cable TV, wireless cable systems, satellite and wireline operators to provide the local and federal authorities with capability to address the American people within 10 minutes during an emergency.

  • Messages can interrupt radio and television to broadcast emergency alert information.
  • Messages cover a large geographic footprint. Emergency message audio/text may be repeated twice, but EAS activation interrupts programming only once, then regular programming continues.
  • Messages can support full message text for screen crawl/display, audio attachments in mp3 format, and additional languages.