The City’s Outdoor Warning System is designed to alert residents
and visitors of San Francisco about possible danger. Specific emergency
announcements can be broadcast over any one of the 65 sirens which
are located on poles and on top of buildings throughout all neighborhoods
in San Francisco, Treasure Island, and Yerba Buena. They are
tested at noon every Tuesday.
During the weekly test, the siren emits a single 15 second alert
tone, similar to an emergency vehicle siren. In the event of a disaster,
the 15 second alert tone will sound repeatedly for 5 minutes
If you hear the siren at a time other than its regular test on
Tuesday at noon:
- Stop what you are doing.
- Stay calm.
- Listen for possible voice announcements.
- Turn on the radio or television, (such as KCBS
740AM, KQED 88.5 FM) for important information provided by the
- Avoid using the telephone. Do not call
9-1-1, unless you have a life-threatening emergency.