San Mateo County, California, has declared a local emergency in preparation for a potentially powerful El Niño season that could bring severe winter weather to the region. The Board of Supervisors approved the declaration on October 20, allowing county agencies to coordinate preparations for the 2026–2027 storm season and encouraging residents to take precautions before dangerous conditions develop.
Officials are warning that the anticipated weather pattern could increase the risk of heavy rainfall, flooding, landslides, coastal erosion, strong winds and power outages. El Niño is a climate phenomenon characterized by unusually warm ocean temperatures in the tropical Pacific, which can influence weather patterns across the United States. Federal forecasts indicate a strong possibility of a strong to very strong El Niño event extending into early 2027, although the timing and severity of individual storms remain uncertain.
The emergency declaration enables county departments and local agencies to coordinate their preparations more efficiently. The county’s Department of Emergency Management will lead the response-planning effort through a dedicated task force responsible for tracking preparations, sharing information and coordinating with local communities and partner agencies. Planned measures include clearing storm drains and culverts, checking emergency equipment and preparing sandbag distribution locations.
Coastal communities face particular concerns because powerful winter storms could coincide with unusually high tides, increasing the potential for flooding and erosion. County Supervisor Ray Mueller warned that severe storms combined with high tides could produce unprecedented coastal impacts. Officials are coordinating with transportation agencies, utilities and other partners to prepare for possible road closures, infrastructure damage and interruptions to essential services.
County officials are urging residents to prepare their homes and families before severe weather arrives. Recommended steps include checking local flood risks, keeping drainage systems clear, assembling emergency supplies, signing up for local alerts and developing an evacuation plan if necessary. The declaration is part of broader preparations across California, where state and local authorities are positioning resources ahead of a potentially damaging winter season. Officials emphasize that El Niño does not guarantee a particular storm pattern, but early preparation could help reduce risks to residents and infrastructure.
