October is officially the start of the wet season for most Hawaii locations — especially windward locations — but one might not know that based on the National Weather Services’ official rainfall totals.
Below average August and September rainfall over the Big Island’s windward slopes has worsened drought conditions in some areas.
“There was a recent brush fire in Ookala in the Hamakua district, which is rather unusual since the area is normally wet enough to mitigate such events,” Kevin Kodama, senior hydrologist for the NWS’s Honolulu office, said earlier this month.
While Hilo sports its normal greenery due to sufficient rainfall, its totals were still well below average, both for the month and year. The airport recorded 6.94 inches for October, 68% of its usual total for the month. That brought the year-to-date total there to 70 inches, 75% of its average for the first 10 months of the year.
Upslope of Hilo town, Waiakea Uka and Piihonua both saw double-digit rainfall for the month, with 11.85 inches and 10.91 inches respectively. But even those totals are less than 80% of their October norms.
Perpetually rainy Mountain View logged less rainfall than Hilo, with 6.32 inches, less than half its usual for the month.
“We had a wet stretch right at the beginning of this month and that’s really helped things on the windward side,” Kodama said. That includes two 24-hour periods where Hilo International Airport logged 3.65 inches and 2.25 inches earlier this months.
“On the east side, I’ve been hearing that catchment tanks are fuller than they were before, definitely, compared to September. And hopefully, going forward … things will be wet enough,” Kodama said. “But there’s still some spots with lingering dryness that we’re hearing about, like the Mana area near Waimea and South Point. They still need some more rain to recover.”
The highest total for the month was reported by the Papaikou Well gauge, with 18.79 inches for the month, which is 119% of its October average. It also saw the rainiest day of the month, with 3.7 inches on Oct. 5.
South Point did receive 2.33 inches 95% of its October rainfall norm, but the Waimea Plain logged just 1.35 inches in October, less than half of its usual 2.92 inches for October. Kodama said South Point and the Mana region are still in extreme drought conditions.
Waikoloa, which sees slightly more than 10 inches of rain in an average year, is at a little above half that total, having received just 0.79 inches last month.
Much of the leeward side of the island received above average rainfall. That includes the Kona coffee belt, which experiences its wet season in the summer months, with all four of its rain gauges receiving well-above-average totals.
Honaunau led the way with 7.9 inches, with Kealakekua reporting 7.61 inches, Kainaliu tallying 6.56 inches and Waiaha receiving 5.41 inches.
“It’s been interesting,” Kodama said. “I’m not exactly sure why that is, but they seem to have had an extension of their summer wet season. October was pretty wet for those folks. All of the Kona slopes coffee belt region were above average, so it’s been interesting.”
It was a fairly dry summer in the coffee belt, however, with gauges reporting below average rainfall in July and August. September was a higher-than-average month, rain-wise, for coffee farmers, but most of that rain fell in a single day.
Coffee has a long harvest season, generally from September through February, but dry conditions starting in late 2021 has affected the harvest, according to Tom Greenwell of Greenwell Farms.
“This year was a smaller-than-normal crop,” he said. I would say it’s one of the smallest crops I’ve seen … because of the short flowering season we had this year.
“From the dry weather last October, November, December, the crop came early, basically. And we have a long harvest here. We’ve got coffee, basically, at every elevation, yeah? But the main part (of the harvest) is over.”
Greenwell said the above-average dry season rainfall in the coffee belt could “make a big crop next year.”
Perpetually parched Ellison Onizuka Kona International Airport at Keahole remained so in October, with just 0.23 inches of rain, slightly over a quarter the month’s norm, hitting the tarmac. But Kaupulehu and Kaloko-Honokohau National Historical Park, both reported higher-than-average October rainfall, with 1.97 inches and 2.37 inches, respectively.
It was also drier than normal at most Ka‘u locations. Pahala and Kapapala Ranch in Ka‘u reported than half their usual October rainfall totals, with 2.32 inches and 1.52 inches, respectively. Kahuku Ranch, however, saw 5.37 inches of rain last month, almost twice its usual October.
Email John Burnett at jburnett@hawaiitribune-herald.com.
