FILE: San Francisco’s outdoor public warning system sirens are not likely to reactivate, even amid reports of possible drone attacks on the West Coast.

An FBI warning of a potential drone attack by Iran on California has put a spotlight on San Francisco’s famous emergency sirens.

Familiar to residents and alarming to tourists, the piercing wail of sirens used to be a staple in the city during the weekly test on Tuesday at noon. Although this type of alarm — reminiscent of an air raid siren — may feel like a useful way to warn of a drone attack, they are expected to remain silent for the foreseeable future.

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The San Francisco Department of Emergency Management shut the sirens down over hardware and security issues in 2019. Originally expected to be upgraded at a cost of $2 million to $2.5 million, the repairs were never completed and the sirens remain silent.

In 2023, they were briefly poised for a comeback after then-Supervisor Aaron Peskin planned to introduce legislation that would fund the repairs. However, the work was never started, with Peskin telling SFGATE in early 2024 they were not added to Mayor London Breed’s budget for the city despite her earlier support for Peskin’s legislation.

Today, the San Francisco Department of Emergency Management said it has a variety of methods to alert local residents of public safety dangers without relying on sirens.

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“San Francisco uses a combination of technologies and methods — including Alert SF, Wireless Emergency Alerts, social media, community networks, and public safety vehicles equipped with public address systems and lights,” Jackie Thornhill, a spokesperson for the department, said in an emailed statement. “These tools were used successfully to evacuate Ocean Beach and the Great Highway in December, 2024 during a tsunami warning. We remain committed to reaching as many people as effectively as possible in an emergency and continue to build on our alert and warning programs.”

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Thomas Cova, a professor in the school of the environment, society and sustainability at the University of Utah, told SFGATE that sirens “are excellent at breaking people out of their routine,” but can also cause issues if people don’t have enough information.

“You want everybody to just stop doing what they’re doing and pay attention, and so they’re great at that,” he said. “… But if you just set off sirens in an urban area, and they’re supposed to be for different hazards, they don’t help much.”

A siren going off in San Francisco could in theory alert to a wildfire risk, tsunami, earthquake or terrorist attack, and Cova said people need the right information about a threat to respond appropriately.

“There’s a lot of research showing that if you give people a warning without enough information for them to take action, you create a lot of confusion, which is kind of what sirens are famous for,” he said. 

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Cova said many cities in the U.S. now rely on text alerts similar to AlertSF to warn people of potential dangers. He pointed out that there are two types of alerts, one sent via a cellular network that people can sign up for and wireless emergency alert such as Amber Alerts that are sent via radio waves to everyone in a specific area.

“The text messaging is superior because it comes with information, you know, it can come with, ‘What is the threat? Who is at risk? What can you do?’” he said. 

Cova said there are still problems with the wireless text messaging alerts, including issues with power outages and the fact that some people in areas where the radio waves can’t reach won’t get alerts, and that the alerts may not help people with hearing or visual impairments. He also pointed out the long-standing Emergency Alert System is still in use and can preempt radio and TV programming but is much less effective at reaching a large population since so many people use streaming and apps for entertainment. 

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In the future, he said, wireless alerts could come from satellites like Starlink, which would help reach nearly everyone in an area. But Cova explained that today, the hope is people who do get the messages can then help others who may have missed the alert. 

“We hope that people take care of each other, check on each other,” he said.

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