SAN FRANCISCO (CBS SF) — San Francisco’s Outdoor Public Warning System, which sounds off during a weekly test every Tuesday at noon, will be going on a two-year hiatus, the city’s Department of Emergency Management said.

The system, which is made of 119 sirens located throughout the city, is used to alert people about emergencies like a tsunami, a contaminated water supply or a radiological attack.

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The alarm, however, will be heard for the last time next Tuesday at noon before the system temporarily shuts down for upgrades.

The upgrades will be installed over the next two years and will cost about $2.5 million, improving the system’s reliability and security.

When asked why the upgrades will take two years, Kristin Hogan of SFDEM said, “It’s resources, it’s time it actually takes to install the equipment. Then after the equipment upgrades take place, there’s testing and so forth.”

“The Outdoor Public Warning System has stood guard in San Francisco since World War II. As we temporarily relieve the antiquated sirens from their watch for much needed upgrades, San Franciscans can be confident that the city will continue to provide timely alerts and warnings,” Mary Ellen Carroll, SFDEM’s executive director, said in a statement.

“Our message has always been that if you hear that siren and it’s not Tuesday at noon, to seek out other information,” Hogan said.

The last upgrades to the system were made back in 2005. Aside from hardware, officials also want to make sure the software is secure from hackers.

In Dallas in 2017, someone hacked into the city’s emergency system and set off 156 sirens; it took two hours to shut them all off.

The last time the sirens were used for a real emergency in the San Francisco was 2012 on Treasure Island, to warn people about contaminated water during a water main break.

As the new upgrades are being installed, the city will continue to rely on other alert and warning tools already in place, like AlertSF, the Emergency Alert System and Wireless Emergency Alerts, as well as social media.

During the upgrades, residents and visitors are being encouraged to sign up for AlertSF, the city’s emergency text message system, by texting their zip code to 888-777 or by visiting

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