Rainfall totals in the Hamakua, North Hilo, South Hilo, Puna and South Kona districts were mostly near- to above-average for September, according to the monthly precipitation summary prepared by the National Weather Service in Honolulu.
The highest daily rainfall totals for the Big Island all occurred during the last five days of the month, Kevin Kodama, NWS Honolulu’s senior service hydrologist, reported.
“Fortunately, none of this enhanced rainfall caused significant flooding,” Kodama said.
The highest daily total reported was 4.08 inches in Honaunau on Sept. 27. That contributed to a monthly total of 11.04 inches recorded there, 156% its September norm of 7.08 inches.
Two of the other three rain gauges in West Hawaii’s coffee belt also recorded higher-than-average totals for September, with Kealakekua at 8.62 inches and Waiaha at 8.43 inches. Only Kainaliu reported lower-than-average rainfall for the month at 6.07 inches.
There was a weak low-pressure system, interrupted by trade winds, that caused brief heavy showers over Hawaii’s Island’s windward slopes in September, resulting in some minor flooding.
The highest recorded rainfall for the month in a populated area occurred at Kawainui Stream near Pepeekeo with 14.51 inches, almost twice its normal rainfall for the month.
Papaikou Well followed closely, with just over 14 inches. That, however, was 88% of its normal 16 inches for September.
All other gauges reporting double-digit rainfall for the month were in windward areas of the island: Piihonua, 13.39 inches; Glenwood, 12.66 inches; Pahoa, 10.77 inches; Laupahoehoe, 10.57 inches; Waiakea Experimental Station, 10.31 inches; and Saddle Quarry, 10.26 inches.
Piihonua has the highest rainfall total for the year thus far, with 149.62 inches, almost 13 inches above its norm. Glenwood, in the upper Puna rainforest, has measured 146.94 inches for the year, about 85% of its norm for the first nine months.
Hilo International Airport logged 8.94 inches, slightly above its 8.7 inches norm for September, bringing it to 97.62 inches for the year, almost 14 inches more rain than its year-to-date average.
On the leeward side, Ellison Onizuka Kona International Airport at Keahole had just 0.16 inches for the month, only 30% of its average, but its 11.49 inches for the year is 4 inches wetter than its usual nine-month total.
Almost all the other leeward gauges tallied below-average rainfall for the month, but most are near or above their year-to-date norm.
Email John Burnett at jburnett@hawaiitribune-herald.com.