Hawaii Waves Swamp Homes, Spill Across Highways

Towering waves on Hawaii’s south shores crashed into homes and businesses, spilled across highways and upended weddings over the weekend.

The large waves — some more than 20 feet (6 meters) high — came from a combination of a strong south swell that peaked Saturday evening, particularly high tides and rising sea levels associated with climate change, the National Weather Service said.

Chris Brenchley, the meteorologist in charge at the National Weather Service office in Honolulu, said several factors came together to create such huge waves.

“Waves over 12 or 15 feet (3.66 or 4.57 meters), those become extremely big and really rare to have,” he said. “It’s the largest it’s been in several decades.”

Brenchley said the swell was produced in the South Pacific, where it’s currently the winter season.

“They had a particularly strong winter storm where the winds were focused directly toward places like Samoa and then further on to the north into Hawaii,” he said.

Remnants of Hurricane Darby passed south of Hawaii but had no major impact on the surf, he said.

While singular events like this hard to pin directly to climate change, Brenchley said the warming planet is playing a role.

“The most direct type of impact that we can use with climate change is the sea level rise. Any time you add just even small amounts of water, you raise that sea level just a little bit,” he said. “And now those impacts will be exacerbated whenever we have a large storm event or a … high, high tide.”

Most large summer swells that come from the south are no bigger than about 10 feet (3 meters), which would trigger a high surf advisory.

“We had some waves that were reaching 20 feet (6 meters), 20 feet-plus even,” Brenchley said. “That’s getting on the level of historic.”

Hawaii’s north shores, where professional surfers often compete, usually get much larger waves than other parts of the islands.

The predominant swell hits the north shores in the winter and the south shores in the summer.