Marin County faces a 90% chance of a significant El Niño event.
King tides during holidays could exacerbate flooding risks.
Residents urged to prepare with sandbags and sign up for AlertMarin.

What's Happening

Marin County officials are ramping up preparations for a potentially severe El Niño event, which has a greater than 90% likelihood of occurring this year, according to the Climate Prediction Center (Marin Independent Journal, 2026). El Niño, a climate phenomenon characterized by warmer-than-usual Pacific Ocean surface temperatures, is expected to bring increased precipitation, atmospheric rivers, elevated flood risks, and potential landslides to the region. County officials are particularly concerned about the compounding effects of elevated sea levels, king tides, and significant storm systems. King tides are forecast to coincide with the Thanksgiving and Christmas holidays, raising the risk of widespread flooding. In January, Marin County experienced severe flooding due to high king tides and a winter storm surge, resulting in $4.3 million in damages, including $2.6 million to a levee in Santa Venetia. Despite these challenges, the county is taking proactive measures to mitigate risks and improve preparedness.

Impact & Risks

The primary risks include flooding, landslides, and infrastructure damage, particularly in low-lying areas and neighborhoods like Santa Venetia. Elevated sea levels, combined with king tides and potential atmospheric rivers, could lead to significant flooding across Marin County. The timing of king tides during major holidays may complicate emergency response efforts. Residents are also at risk of power outages and road access issues due to fallen trees and poles during storms. The county has identified 32 locations for sandbag distribution and is enhancing its emergency notification system to provide earlier warnings for severe weather events.

Forecast & Timing

The El Niño event is expected to bring heightened precipitation and storm activity to Marin County throughout the fall and winter months. King tides are forecast to occur during the Thanksgiving and Christmas holidays, potentially coinciding with atmospheric rivers and storm surges. The county plans to issue weather warnings up to five days in advance, with thresholds including 2 inches of rain in one hour, 3 inches in 24 hours, tides exceeding 7 feet, or sustained winds over 30 mph. A new radar network will provide high-resolution, location-specific forecasts to aid in preparation and response efforts.

Guidance & Precautions

Residents are urged to prepare for potential flooding by securing sandbags in advance, as supplies may run out during emergencies. The county recommends signing up for AlertMarin to receive timely weather warnings and emergency updates. Homeowners are encouraged to inspect and clear drainage systems on their properties and collaborate with local community organizations to enhance preparedness.