Forecasters predict a slow start to Hawaii's rainy season

Oct. 16—Hawaii residents likely won't need to pop open an umbrella very often for the rest of the year.

Climate scientists predict the state's rainy season from now through April will have a drier-than-average start through December, followed by wetter-than-average months—repeating a pattern similar to 2020.

The National Oceanic and Atmospheric Administration on Thursday declared the presence of La Nina weather conditions for a second consecutive year, and the agency's National Weather Service office in Honolulu forecast Friday that La Nina's intensity should be a moderate one, producing similar weather as 2020 with above-average total rainfall despite a late start.

"I'm calling for a dry start to the wet season, " senior service hydrologist Kevin Kodama said Friday during a media briefing. "We're looking at the second half of the wet season to be fairly wet."

La Nina, the opposite of El Nino, denotes cooler-than-average sea surface temperatures in the Central and Eastern Pacific Ocean near the equator.

This tends to result in a busier Atlantic and quieter Central Pacific hurricane season.

Moderate La Nina conditions should result in heavy rainfall primarily on windward slopes while leeward areas remain dry, Kodama said.

Last year's wet season was forecast to be stronger but ended up as moderate.

Still, Kodama said 2020's wet season was around the 10th wettest on record.

This year the intensity of La Nina is expected to be about the same or a little weaker than 2020, though Kodama said National Weather Service modeling used to make the forecast showed that some deviation would not be surprising.

"There was quite a bit of spread in the model projections, so the confidence level wasn't extremely high, " he said. "So we'll have to see."

Hawaii is entering its wet season following a fairly extreme dry season that ran from May through September, according to Weather Service data.

Though most areas in the state measured for rainfall had near-to below-average rainfall, 2020's dry season ranked as the sixth driest in the past 30 years, based on eight key measurement sites.

At Daniel K. Inouye International Airport, rainfall during last year's dry season was the lowest in 30 years.

The recently ended dry season started early and led to severe drought statewide, with the worst impacts in Maui County and on Hawaii island, according to the Weather Service.

Severe drought began in early May on Hawaii island, then occurred for Maui County by late June before turning extreme by late July.

On Oahu severe drought conditions hit in late July. Kauai had the same in September.

Kodama said impacts from these conditions included the Mana Road brush fire on Hawaii island, water conservation requests for Upcountry Maui and losses of cattle and crops on Maui. Some of the crop losses were from axis deer invading farms to find food after the natural vegetation they typically eat dried up, Kodama said.

With the expected wetter rainy season ahead, there is more potential for drought recovery statewide.

"Wet season weather systems have a greater chance of reaching both Kauai County and Oahu before they stall out or dissipate as they're moving eastward across the chain, " Kodama said.

He added that it's possible that because of the intensity of drought on Maui and Hawaii island, those conditions might still exist after this year's rainy season is over.

"That's definitely a possibility, " Kodama said. "Hopefully, that won't happen."