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National Weather Service says rainy season started slow in October, with 2 record low rainfall totals on Oahu

The start of the wet season in October ended up relatively dry for some parts of Hawaii, according to weather officials, particularly for the leeward sides of Oahu and Maui.

On Oahu, almost all rain gauges had below average totals, according to the National Weather Service’s rainfall summary for the month. On Maui County, most gauges were also below average, with the exception of a few along windward slopes that were near to above average.

Two record low rainfalls were also logged on Oahu — at Honolulu Airport and Aloha Tower. Bellows Air Force Station and Makua Range recorded their lowest October totals since 2007.

At Honolulu Airport, a mere 0.05 inches of rain fell in October, the lowest level in more than 50 years, according to NWS senior service hydrologist Kevin Kodama. The previous record was 0.07 inches in October 1996.

The average amount of rainfall for Honolulu Airport in October is at 1.51 inches.

Kodama said a combination of factors were at play, with persistent trades at the start of October which brought rain to the windward side, but not Honolulu Airport, followed by a more stable pattern in the second half of he month, which kept conditions dry.

At Aloha Tower, only 0.14 inches fell in October, the lowest on record over 30 years, when the average there is 2.55 inches.

In its mid-October forecast, NWS said it expected above average rainfall for the wet season — which runs from October to April, with a few driver-than-average months to start.

Kodama said rains in October and this month were expected to remain low, followed by December as a transition period, then above average rainfall from January to April.

For areas suffering from severe drought — present in all four major counties — there is still no relief in sight.

NWS says severe drought is present in the lower leeward slopes of Kauai from Hanapepe to Waimea, the lower leeward slopes of Oahu from Kapolei to Waianae, and portions of South Kohala, North Kona and Hamakua districts on the island of Hawaii,

The worst drought continues on Maui, where extreme drought has entered its fourth month along the lower leeward slopes of Haleakala, and has spread to the leeward areas of Molokai and Lanai.

The leeward sides of Oahu, Maui and Hawaii island all experienced below average monthly totals. In leeward Maui, all gauges from Kihei to Maalaea reported no measurable rainfall for the month.

In parts of Maui’s Central Valley, there is now exceptional drought, which is worse than extreme drought.

Whether there is any relief depends on the strength of the La Nina season this year, said Kodama, which may end up being moderate to strong, and bringing above average rainfall to windward slopes, but not the leeward sides that need it.

“With a drought this significant in Maui County, you need multiple rain events,” he said.

On the island of Hawaii, windward slope gauges were near to above average, while the rest of the island remained mostly below average.

The Saddle Quarry gauge recorded the highest 24-hour total of the month with 11.39 inches from noon Oct. 11 to noon Oct. 12. The two-day heavy rain event helped push the Hakalau monthly total to its highest October value since records started at this site in 2004.

In contrast, the Honaunau and Kealakekua gauges had their lowest October totals since 1995.

On Kauai, windward gauges recorded mostly near to above average totals while leeward gauges reported below average totals.

“We were expecting a slow start to the wet season,” said Kodama, adding that January through April are the months to watch for more rains.

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