The National Weather Service’s Honolulu office on Wednesday released its 2020-21 wet season summary for October through April and its 2021 dry season outlook for May through September.
“On the Big Island, the North and South Kohala districts had mostly below-average rainfall with 30% to 70% of average, and the rest of the Big Island’s totals were greater than 100% of average,” said Kevin Kodama, NWS Honolulu’s senior service hydrologist. “… Hilo airport had its seventh-wettest wet season in the last 30 years.”
The airport logged 101.73 inches of rain between Oct. 1 and April 30.
The mountain slopes of the Kona coffee belt, which experiences its rainy season during the summer, are also forecast to be drier this year than in recent years, according to Kodama.
Kodama said the drought that returned to leeward North and South Kohala is expected to worsen during the summer.
“We’ll possibly or maybe even probably be seeing extreme droughts — or the D3 drought monitor category — again by the end of September for portions of leeward Maui County and leeward Big Island,” he said.
Kodama said even windward areas could experience moderate or severe drought this summer.
“But windward drought is different,” he explained. “And what you’ll see during the summertime with windward drought is that it often involves a normal number of days with rainfall but a lower-than-normal amount of rain per day. … So this means that water supply systems that depend on surface water or rainfall catchment will be the most vulnerable to this type of condition.”
The weather service reported five record-tying days of heat this month at Hilo airport — but Kodama said the forecast for the Hilo summer is for days to be cooler than normal. In fact, at least some of the record-book entries appear to be what John Bravender, NWS Honolulu’s warning coordination meteorologist, described as the result of a computer glitch.
“In the past few days, the temperatures have been unusually high,” Bravender said. “We sent a technician to the airport, and he compared the automated sensor with a manual observation and realized it was reading high. So he replaced the sensor on the automated equipment.
“And we’ve also voided a couple of those recent records.”
Email John Burnett at firstname.lastname@example.org.