Unprecedented coastal flooding is increasingly impacting Southern California communities as record-high sea levels combine with unusually warm ocean temperatures and a strong El Niño event. On Monday morning, high tides caused flooding in Newport Beach’s business districts and submerged part of Pacific Coast Highway near Sunset Beach. Sea levels at the Los Angeles Harbor in San Pedro reached a record 8.02 feet above the baseline, surpassing the previous record set in 2005.

Scientists attribute the flooding to a confluence of factors. Primarily, ocean waters along the California coast are at historic high temperatures for this time of year, stretching from the Farallon Islands near San Francisco down to Baja California. These elevated sea surface temperatures cause thermal expansion, meaning the warmer water occupies more volume, raising sea levels beyond what astronomical tides alone would account for.

The current sea surface temperatures, recorded at locations such as Scripps Pier in La Jolla, are roughly 9 degrees Fahrenheit above average. This extreme warmth is being driven by one of the most intense El Niño events in recent history. El Niño, a climate pattern characterized by warming of sea surface temperatures in the central and eastern tropical Pacific, amplifies conditions along the North American west coast. Some experts compare this event to or consider it even stronger than the monumental 1997 El Niño, which led to extensive global damage.

Additional factors are also contributing to the heightened coastal flooding. A Kelvin wave—a slow-moving pulse of warm water originating in the equatorial Pacific—passed near the California coast earlier this month, along with swells from Tropical Storm Rachel, both of which pushed sea levels higher. Meanwhile, cyclical astronomical influences related to the moon’s orbit—the 18.6-year lunar node and 4.4-year lunar perigee tidal cycles—are currently near their peaks, further elevating tides. These combined influences have contributed to flooding in areas from Newport Beach to Long Beach and Sunset Beach, with residents and officials scrambling to mitigate impacts through sandbagging and pumping out water.

Local community members have observed the stress placed on coastal infrastructure. In Naples, Long Beach, residents reported seawall breaches and expressed concerns about the aging barriers’ ability to withstand ongoing high tides and future “king tides” expected around upcoming holidays. Some warned that sustained flooding could lead to more severe property damage if higher tides coincide with strong storms, as occurred during the historic 1983 storm aligned with a major El Niño.

Although scientists had anticipated elevated sea levels and related flooding from the strengthening El Niño, conditions appear to have arrived sooner than expected. The unusually active 2026 hurricane season in the eastern Pacific, typical during El Niño years, also contributed earlier by producing remnants of Hurricane Marie that caused flooding and infrastructure damage in areas such as Long Beach and Malibu.

Experts note that the persistently warm ocean conditions are abnormal and raise ecological concerns, potentially affecting local marine life, plankton, and bird populations. As the coastal region braces for more extreme tides and possible storms in the coming months, officials and residents remain vigilant about ongoing flooding risks along Southern California’s coastline.