Posted on October 15, 2026
By Kevin Wallis
Contrary to what you may have heard, the recent wave run-up flooding in places like Newport Beach wasn’t caused by a single “El Niño storm.” It resulted from events that began weeks, months, and even years ago, combined with several factors that converged on Friday, October 9th. In rough chronological order:
- Long-term beach erosion. In some spots this began years ago, but it went into overdrive over the past few months thanks to a relentless series of strong southerly swells, both Southern Hemisphere and tropical in origin, associated with El Niño.
- Large, overlapping southerly swells on October 9th. Mid-period energy from Hurricane Rachel combined with very long-period energy from a SSW Southern Hemisphere swell. The two occasionally phased together (constructive interference), amplifying wave run-up. Standing on the beach Friday, you could see the long-period Southern Hemi swell periodically “catch up” to the shorter-period tropical swell, doubling up and pushing waves farther inland. As my colleague Jax Richards noted in his excellent Instagram post on the event, Newport has a history of beach flooding during very long-period SSW swells, most recently on July 3rd, 2020.
- Water levels running more than a foot above normal. Two things drove this: thermal expansion (water’s increase in volume as it warms), with sea temps running 5–10+ degrees above average in SoCal and across most of the Eastern Pacific, and the ongoing coastally trapped Kelvin wave. Friday’s predicted high tide was just under 6′, but nearby tide stations observed close to 7.5′. Long-term sea level rise also played a role, though likely a much smaller one than the other factors.
