“The first month of the 2024 dry season started with a week of trade winds and rainfall mostly linked to the east-facing windward shores. That was the end of the dry conditions.”
That’s how Kevin Kodama, senior service hydrologist for the National Weather Service in Honolulu, summed up weather conditions for the month of May, traditionally the start of Hawaii’s dry season.
“Big Island rainfall totals were near to above average at most of the rain gauges,” Kodama said in his monthly precipitation report.
He described Honokaa as a “notable outlier.” The Hamakua hamlet got just 1.78 inches of rain in May, 27% of its average of 6.63 for the month.
Much of the heavy rainfall occurred on May 10 when strong midafternoon thunderstorms over the Hilo area generated rainfall rates of 3 to 4 inches per hour, causing flash flooding downtown and brief power outages.
While the thunderstorms abated and moved offshore by sunset, heavy rainfall started by 9 p.m. that night over the South Kohala slopes. The showers moved slowly toward Puako and the Waikoloa Beach areas, with rainfall totals of 3 to 6 inches between Waimea and Kawaihae.
Waikoloa, almost always arid, ended up with 5.4 inches of rain for the month, more than five times its norm.
Another windward deluge occurred May 13, when 6.19 inches fell near Kurtistown.
Kona lows on May 18-19 and May 23 dropped rain on Oahu and Kauai, but had no major effect on the Big Island.
Hilo International Airport recorded 9.75 inches of rain in May, 139% of its norm. Piihonua, on the Mauna Loa slope above Hilo, received 22.21 inches, 165% of its May average. A total of 21.57 inches fell in Glenwood, in the upper Puna rainforest, 36% more than its usual May rainfall.
In Ka‘u, Pahala had its highest May rainfall total since 1965, with 14.34 inches, while Kapapala Ranch’s rainfall of 11.1 inches is its highest May total since 2002.
The Kona coffee belt, which has its wet season in the summer, recorded above average rainfall in all four of its official gauges.
Waiaha had the most abundant rainfall in the region, 10.51 inches, more than twice its May norm. Kealakekua, Kainaliu and Honaunau received 9.39, 8.85 and 6 inches even, respectively.
Even with mostly above average rainfall, much of perpetually dry North Kona remained so.
Ellison Onizuka Kona International Airport in Keauhou received almost twice its normal May rainfall, but that amounted to just 1.21 inches. Kaloko-Honokohau tallied 1.67 inches, 95% of its norm, and 2.4 inches fell at Kaupulehu, 60% above norm.
State officials held a press conference June 4 on Maui to reiterate that a drier-than-usual dry season has been forecast, as well as a deepening drought during the summer.
“Parts of south Maui and western Hawaii Island are already in severe drought conditions,” said Mike Walker, the Department of Land and Natural Resources Division of Forestry and Wildlife’s fire protection forester.
“Much of the state received above-normal rainfall in April and in parts of May, but that didn’t happen across the entire island chain,” added Derek Wroe, a National Weather Service forecaster. “So, parts of Maui and the Big Island have remained in drought. And as we move into the summertime … the drought that’s in place on Maui and the Big Island will likely worsen, and the drought will expand to all Hawaiian Islands.”
