Every Tuesday at noon, 65 air raid-style sirens around the city sound off for 15 seconds as a test for an emergency warning system. In a real emergency, the sirens will cycle continuously for around 5 minutes and will broadcast instructions instead of "this is a test." Those with access to radios should tune in to KCBS 740 AM, KQED 88.5 FM or a local news channel should this happen. In some parts of the city, such as in SoMa, the "test" message is inaudible, at least from indoors. If you work in the Financial District the siren can be fairly jarring, to say the least.
A digital sample of the siren can be heard here: 
siren.wav.
The San Francisco Office of Emergency Services & Homeland Security urges those who live or work in San Francisco to consider the siren as a weekly reminder to compile an emergency-preparedness kit capable of sustaining themselves and their dependents for 72 hours. ![[WWW]](http://wikispot.org/wiki/eggheadbeta/img/sycamore-www.png){kind=small}
72hours.org provides details on how to prepare for an impending emergency as well as what to do in the event of a natural disaster, terrorist attack, or epidemic.
More information on sfgov.org
