Slightly soggier than expected 2023-24 wet season will buffer Hawai‘i from earlier onset of drought, wildfire season

If you think the most recent Hawai‘i wet season, from October 2023 through April, was somewhat soggier than expected, you didn’t have your head in the clouds.

National Weather Service Senior Service Hydrologist Kevin Kodama, who works in the Honolulu forecast office in Honolulu, said Tuesday morning that the state wasn’t as dry as anticipated and ended the wet season with near to below-average rainfall at most locations.

That’s a good thing as the dry season sets in.

The extra rainfall through April added to what the state has gotten so far this month, including from last week’s kona low and the heavy rains and thunderstorms that drowned the Big Island the week before, will provide a buffer against the earlier onset of expected drought conditions later this summer — and wildfire weather.

A quick transition from one of the strongest El Niños observed to La Niña conditions also means there likely will be fewer tropical cyclones — which include tropical depressions, tropical storms and hurricanes — moving through the Central Pacific during the 2024 hurricane season.

Conditions were much different when the wet season began last fall.

“It’s one of those things where when you think you know, have a pretty good handle on the situation — our forecast at the time we had a high level of confidence — and you think you got things under control and you know what’s going on, Mother Nature comes around and says, ‘No you don’t,'” said Kodama during a news conference to announce the outlook for the 2024 Central Pacific hurricane season.

Portions of all four of the state’s counties were in severe drought; some places on the Big Island and Maui were even in extreme drought.

El Niño, which causes the surface temperature of water around the equator to warm above normal, was in place and intensifying. It peaked as a strong-level event late in 2023 and has weakened through spring.

That played a big part in the amount of rainfall the islands saw during the past 7 and a half months.

With El Niño in place, along with forecast models and other guidance, everything leading up to the wet season pointed to below-average rainfall, consistent with what is normally expected when those conditions exist.

From October into mid-November last year, the state remained parched as most areas recorded below-average rainfall. Several rain events after and through January took the edge off the drought, bringing some much-needed relief to the islands.

That was already out of the ordinary for being in a strong El Niño.

In February and March, conditions dried out again. Kodama thought the originally predicted dryness was finally rearing its head. In fact, leeward areas of Maui and the Big Island started to see severe drought pop up again.

However, by mid-April, at the tail end of the wet season when conditions are expected to start calming down, the state experienced some heavy rainfall, with wet conditions from Kaua‘i to Moloka‘i.

Some locations in south Kaua‘i saw record rainfall for the month of April and there was quite a bit of flooding on the island’s south side.

That precipitation unfortunately never reached the east half of the state completely, so drought continues to persist for portions of the Big Island and Maui.

The wet season ended up being Hawai‘i’s 10th driest in the past 30 years. Forecasters thought it was going to be worse. Kodama wouldn’t have been surprised, going into the season, if the state would have ended up having one of its top 5 driest wet seasons.

Most areas on the Garden Isle saw near to above-average rainfall, with most rain totals of 110% to 150% of average.

A majority of windward locations on the Big Island had about 50% to 80% of their average rainfall. The rest of the island, was definitely in the below-average category, at 30% to 60% of their average.

Hilo International Airport saw 58.63 inches of rain and its seventh driest wet season in the past 30 years. On Kaua‘i, Līhuʻe Airport recorded 27.89 inches for its 14th wettest in the same time period with near-average rainfall.

El Niño continues to weaken and La Niña, a cooling of water surface temps around the equator, is taking its place. Once La Niña conditions mature, they are expected to persist into the early part of 2025.

That’s perfectly normal, Kodama said, as is the below-average rainfall predicted for the rest of Hawai‘i’s dry season, which runs from May through September. It’s also the consensus of climate models for the dry season and consistent with what forecasters would expect during a La Niña summer.

Dry season rainfall totals will be skewed this year, however, mostly because of the amount of precipitation the islands have received through the first part of May.

As an example, the Daniel K. Inouye International Airport in Honolulu as of Monday had recorded 4.90 inches of rain this month, which is already past its average for May through September, putting it above its dry season average right out of the gate.

The state just had the latest kona low to directly affect the main Hawaiian Islands in the past 20 years. The heavy rains that drenched O’ahu from that storm as well as a good amount of rain at the end of April and beginning of May in other parts of the state, including the Big Island, should help delay the return of significant drought.

The only exceptions would be leeward slopes of Haleakalā on Maui and interior sections of the Big Island, where drought has persisted. Conditions in those areas will likely only worsen in the coming weeks and months.

Non-irrigated agriculture and water systems that depend on surface water diversion will see the most significant impacts as drought develops and persists later this year.

“So we’re talking about places like Upcountry Maui and any residents that are on water catchment systems,” Kodama said. “They’ll be feeling the impacts of the drought first, or the earliest, and also will have the most severe impacts as the drought goes on.”

The late wet season rainfall and extra precipitation so far this month will also have an impact on significant wildfire risk throughout the state, “and what I mean by significant is big ignitions and runaway ignitions,” he said, pushing the wildfire season back to after the normal late July into early August.

Again, with the exception of the already drought-stricken leeward slopes of Haleakalā and interior sections of the Big Island.

The onset of La Niña conditions is also a key factor in how hurricane season, which runs from June 1 to Nov. 30 in the Central Pacific, plays out this year.

Forecasters with the National Oceanic and Atmospheric Administration’s Central Pacific Hurricane Center and Climate Prediction Center say the 2024 season will be below average, with one to four tropical cyclones predicted to move through the entire basin.

A near-normal hurricane season has four to five tropical cyclones.

There is a 50% chance of below-normal tropical cyclone activity this year, 30% chance for a near-normal season and just a 20% probability of above-normal activity. That doesn’t mean, however, any storms that move through the Central Pacific will directly impact Hawai‘i.

La Niña typically spikes wind shear near Hawai‘i and over the entire Central Pacific basin, which tears apart low-pressure systems and any storms that do form from the top, making it harder for tropical cyclones to develop or survive.

The Central Pacific had a near-normal hurricane season in 2023, with four cyclones moving into the basin and two others that came close as they moved through the Eastern Pacific.

That included Hurricane Dora, the first major hurricane to move through the Central Pacific since 2020, reaching Category 4. The storm also was only the second tropical cyclone on record to maintain hurricane strength as it moved through the Eastern, Central and Western Pacific basins.

Dora stayed far to the south of the Big Island and never made landfall in the state, but a strong gradient created between the storm and high pressure to the north resulted in strong damaging winds blowing dry air across the islands.

Those winds fanned deadly flames of destruction Aug. 8 on Maui as a fast-moving wildfire swept through and devastated the historic community of Lahaina, killing more than 100 people. It was the deadliest wildfire in U.S. history in more than a century.

The same winds contributed to the spread of wildfires the same day in Kohala on the Big Island. They were fortunately much smaller and less destructive than the Lahaina blaze. They were mostly in unpopulated areas and caused no deaths.

Dora last year and Hurricane Douglas in 2020, which made a closer than comfortable approach to the islands as it skirted along the north of the state in a year that also saw a below-normal hurricane season, are two recent examples of storms that never made landfall in Hawai‘i but still had major impacts or threatened the islands.

“So it’s important to remember the numbers don’t tell the whole story for the potential for hurricane threat for Hawai‘i,” said Chris Brenchley, director of the Central Pacific Hurricane Center, toward the end of his season outlook announcement.

Gov. Josh Green recently proclaimed May 19-25 as 2024 Hurricane Preparedness Week in Hawai‘i. James Barros, administrator of the Hawai‘i Emergency Management Agency, presented the governor’s proclamation during Tuesday’s news conference.

“Preparedness is all of our business,” said Barros. “Starting with the individuals to their families, building in the neighborhood and communities. … and this year, if feels very much like a kakou [as in we are all in this together] thing as we’re getting ready for this preparedness hurricane season.”

The week is focused on raising awareness about what residents can do now, when the weather is still relatively quiet, to safeguard their homes, business, families and themselves.

Aphirak “AP” Bamrungruan, executive director of the Hawai‘i Office of Language Access, said as people throughout the islands prepare for severe weather, including the upcoming hurricane season, they might also extend their efforts to their neighbors. Particularly those who do not use English as their primary language.

“They are among the most vulnerable population in our state,” said Bamrungruan.

He said a lack of English proficiency impacts people’s safety and wellness, putting them at risk in situations where they are unable to understand written or verbal warnings about dangerous conditions, prepare for severe weather, or respond and communicate appropriately during emergencies.

That’s 1 in 9 people in Hawai‘i who have limited proficiency in English and a significant number of visitors to the state who also speak a language other than English as their primary way to communicate.

John Bravender, warning coordination meteorologist with the Central Pacific Hurricane Center, said it might be somewhat difficult to get ready for hurricane season when it seems like the wet season just doesn’t want to let go, but now is exactly the right time everyone should.

Brenchley added after he presented the 2024 hurricane season outlook Tuesday that he appreciated the messages shared about community preparedness during the news conference.

“It’s very important to remember everyone, the entire community, as we face the potential threat of a hurricane,” said Brenchley. “It’s important to prepare for that threat this season and not wait for a season where we expect it to be more active. Any action that you take now, however small, helps the community to be more resilient in the event of a storm impacting the community.”

For more about hurricane preparedness, click here. Find hurricane safety tips and resources here.

Maps for the 2023-24 wet season are available online for the Big Island and Kaua‘i.

To find current weather conditions and any advisories, watches or warnings, visit the National Weather Service Honolulu forecast office website. Check drought conditions online via the U.S. Drought Monitor.