Everything You Need to Know About Hawai‘i’s Record-Breaking King Tide

What is a king tide and when will it occur again?

By Ashley Mizuo

Photos: Aaron K. Yoshino

When ocean waters poured over Hawai‘i’s sea walls and flooded the streets on Memorial Day Weekend, “king tide” became a new catch phrase. However, king tides occur every year.

“King tide” is a term to describe the highest tides of the year that usually occur during the summer and winter months, experts at the University of Hawai‘i at Mānoa say. The April and May king tides are particularly special because of their abnormally large size. The April king tide surpassed Hawai‘i’s 112-year-old record—raising 9 inches above the predicted tide levels, according to the National Oceanic and Atmospheric Administration.

“We have some unusual oceanographic phenomena occurring related to the recent El Niño, plus warming of the ocean going into the summer, plus long-term sea level rise, plus a swell,” says Chip Fletcher, associate dean of the School of Ocean and Earth Science and Technology at the University of Hawai‘i at Mānoa. “All these together created a ‘stacking’ effect that led to the high water.”

These anomalies are expected to continue through the summer and could affect the size of future king tides occurring June 23–24 and July 21–22. NOAA predicts that the June and July king tides will be higher than both the April and May tides.

“If there is a swell event that arrives, we could see even worse flooding in June and July,” Fletcher says.

This could mean trouble for coastal areas such as Waikīkī’s Hilton Hawaiian Village, which canceled its Friday night fireworks show over Memorial Day Weekend due to potentially dangerous conditions caused by the king tide. The local impacts of the king tides include coastal erosion, wave over-wash and flooding. However, the effects could be exacerbated by oceanic anomalies, swells and even heavy rainfall, according to NOAA.

What happens to the tides after summer? The truth is, no one really knows.

Mark Merrifield, an oceanography professor at the University of Hawai‘i at Mānoa, predicts that, although the king tides will subside, oceanic anomalies may result in slightly higher tides throughout the year. While these anomalies are not permanent, sea level rise is.

“These nuisance flooding events will come and go depending on ocean conditions,” Merrifield says, “but they will steadily become more and more frequent—not just the king tide but a large fraction of all high tides [will] start to reach flood levels with rising sea levels.”

What’s alarming about the April and May king tides is that they give us a glimpse of what will eventually become the norm, according to John J. Marra, NOAA’s Regional Climate Services Director.

“The tides are also being elevated a very small amount over time by rising sea levels associated with global warming,” Marra says, “so, at some point in the future (20 to 30 years), what you are seeing now as a result of the anomaly will eventually be what you see all the time at high tide.”

Missed witnessing the recording-breaking king tides? Don’t worry, we were there—and we took photos. Check them out below!

If you have before and after photos of the king tide, click here to send them to the Hawai‘i and Pacific Islands King Tides Project, run by the University of Hawai‘i at Mānoa.