San Mateo County launches storm warning system ahead of El Niño

Originally published on October 31, 2026 by the San Mateo Daily Journal and written by Ana Mata.

A new emergency system in San Mateo County will better forecast storms and prepare the local community ahead of potentially dangerous weather during this upcoming holiday season, San Mateo County leaders announced in a press conference Friday. 

Supervisor Ray Mueller, joined by other legislators and emergency management leaders, shared what the county is doing for storm prep, and called upon residents to chip in too. 

“This year is an El Niño year and we have entered a critical time of preparedness,” Mueller said. “This is crunch time.” 

Meanwhile, the county’s Emergency Management department announced the launch of the Atmospheric River Emergency System. This tool will give earlier, local warning ahead of severe storms, which will aid in the county’s emergency operations to stage crews, warn residents and ready resources before storms peak. 

The emergency system was developed by Dr. Marty Ralph with the Center for Western Weather and Water Extremes at UC San Diego. The county engaged in the partnership as “their data shapes how we prepare for the season ahead,” Emergency Management Director Dr. Shruti Dhapodkar said. 

“First responders and emergency managers have always worked ahead of the storm,” Dhapodkar said. “ARES lets us see further out and closer to home.”

During El Niño, the climate pattern where the temperature of the Pacific Ocean rises above normal, a combination of hazardous conditions could present a higher risk of damaging winter weather. 

Atmospheric rivers are the particular type of storm that could determine how devastating this winter may be to local infrastructure, Ralph said. 

These storms are categorized on a scale from one to five. One would be a storm that is “primarily beneficial, sometimes hazardous” while five would be a storm that is “primarily hazardous, sometimes beneficial,” Ralph said. 

More so than any one storm’s strength, a combination of multiple atmospheric river storms, or their coupling with king tides — which are estimated to occur around the Thanksgiving and Christmas holidays — is more relevant. 

While a level one storm could be considered good for water supply, if it happens the day after a level five storm, it would be what sets local infrastructure over the edge, Ralph said. 

“When you hear about the [atmospheric river] ranking, think about it carefully,” Ralph said. “Think about your vulnerability, your community, is the landscape wet or dry, are the rivers already full or not, and what are your vulnerabilities personally to have a better sense of the impact of that storm.”

Federal perspective

As regions across the state brace for the impact of this year’s anticipated historic El Niño season, U.S. Rep. Sam Liccardo, D-San Jose, applauded San Mateo County’s work in partnership with a data-driven system like ARES. 

“We can respond with one of two tools — We can either use a Sharpie, or we can use science,” Liccardo said, referring to President Donald Trump’s infamous Sharpie-altered map of Hurricane Dorian. “Here in San Mateo County, they rely on science.” 

Ensuring that the data is localized and relevant to San Mateo County will be easier with the new ARES program, U.S. Rep. Kevin Mullin, D-South San Francisco, said.

“Not all cities will face the same threats; California is massive and even various communities in the Bay Area will be impacted differently,” Mullin said. That is why it is essential to have localized information and the ability to communicate directly with those impacted.” 

While the county is working to have the right data to keep residents safe, Mueller reiterated the need for residents to still do all they can now. 

The new emergency system “does not, in any way, mean that we do not need people to prepare now,” Mueller said. 

Residents can also check in with their neighbors, families and colleagues now, before a storm arrives, Dhapodkar said. 

“The best science in the world is worthless if we don’t plan together and do something about it,” Dhapodkar said. “ARES gives us the data, but we need to take action, which means every single one of us. 

“Communities that weather the storm well are the ones that are connected,” Dhapodkar said. “Small connections now make all the difference when the storm arrives.” 

READI Act

Residents that may have accessibility or functional needs and possibly live in areas prone to power outages or poor cell reception are asked to contact the county’s department of Emergency Management or their local fire departments and register. This way, local emergency responders will have a comprehensive list of where residents may be and how to reach out if necessary. 

Communicating with residents in the case of an emergency is also the focus of a new bill sponsored by Mullin, which he announced at Friday’s press conference, alongside the county’s implementation of ARES. 

The Reliable Emergency Alert Delivery Integrity Act, directing the Federal Communications Commission to improve the performance of the wireless emergency alert system. 

This tool is used to send geotargeted alerts to cellphones. During recent disasters, flaws in the system have been exposed, including alerts sent to the wrong demographic of residents, causing chaos and slow response times.

“Alert failures erode public trust and one in six Americans has turned over the emergency alert on their cellphone,” Mullin said. “Emergency alerts can make the difference between life and death.” 

Mullin’s proposed READI Act would evaluate if these alerts are reaching those necessary in a timely manner and require wireless providers to warn users before they opt out. It would also require the FCC to look into advanced translation technologies to provide information to non-English speaking communities. 

“Every minute counts during a crisis and timely, accurate information is the most precious tool we have to prevent property loss, injuries and death,” Mullin said. 

During the press conference, Ralph spoke about the work that has been done in the last decade to better prepare San Mateo County — and regions throughout California — for this upcoming season.

“This is a story of innovation and science progressing quietly, often behind the scenes, supported by leaders like the officials we have here, supporting against sometimes great headwinds,” Ralph said. “That support has enabled these new tools to become available. “ 

Residents can visit www.smcalert.info to sign up for cellphone alerts related to local emergencies.

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