Outdoor Public Warning System

What is the OPWS for?

The City’s Outdoor Public Warning System is designed to alert residents and visitors of San Francisco about possible danger. Specific emergency announcements can be broadcast over any one (or more) of the 109 sirens which are located on poles and on top of buildings throughout all neighborhoods in San Francisco, Treasure Island, and Yerba Buena.

Why do the sirens go off every Tuesday?

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

What if I hear the siren at another time?

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 740 AM or 106.9 FM, or KQED 88.5 FM) for important information provided by the City.
  • Avoid using the telephone. Do not call 9-1-1, unless you have a life-threatening emergency.

On rare occasion, special tests are done on other than Tuesday at noon - we will make every effort to inform the public of the date and time before these tests occur.

Do you know where YOUR siren is?

Download the map of Siren locations here (PDF) February 2015
Download the list of Siren locations here (PDF)

Then let us know how well YOUR siren is working! Check the Twitter feed to the right for sirens that the city knows are non-operational, or sirens requiring extra attention.

You can help improve the OPWS!

If you are an Amateur Radio Operator, you can check in to Siren Net and give us a report of what you hear during the test. This net is conducted by the Auxiliary Communications Service on the 1st, 3rd and 5th Tuesday of each month. It starts just before noon, and check-in with reports begins after the sirens sound at noon.  All licensed Amateur Radio Operators are welcome to participate. The net runs on the linked UHF/VHF repeaters owned by the George S. Ladd Telephone Pioneers: 443.100/+ DCS 114 and 146.790/- tone 114.8.

Net controls: Please visit the ACS Resources Page to download the latest version of the script.

If you do not have an Amateur Radio License or are not able to check-in on the siren net, we have another way for you to report the weekly test of your siren - an online form!  This link will take you to the survey form to report your siren performance