Dry October for Big Island ends with much needed precipitation and return of rainbow season

Gloria Silva-Sampaio’s 1,550-gallon water catchment tank in Puna was less than half full at one point in October, and she had to use part of that water for her five sheep, two dogs and four cats to drink.

Without water coming into the catchment tank on a consistent basis, mosquitoes and their larvae became so bad that she had to add bleach to kill them. The dry weather also was causing her grass to get burned by sheep urine.

The wet season is supposed to start in October for the Big Island, but there were several days when Puna residents reported no rainfall at all or just a trace to the Puna Weather Facebook group.

It was so dry, some residents had to get water delivered because their catchment was running dry.

Georgia Garman in Hawaiian Paradise Park asked if if would ever rain again in an Oct. 11 post to the group. “I miss the rain. I just do. I watered this morning. Never done before in the year we’ve lived here.”

While she was posting, rain started to fall, providing her with an “Ahhhhhh” moment.

“Rain what rain?” asked Tommy Carson in a reply to a public Oct. 16 post in the group.

“[ʻĀinaloa] 6:55 PM, some scattered showers last night and today, still need SERIOUS rain,” replied Sherrie Moore to another public post in the group Oct. 18.

“Nothing in the [ʻĀinaloa] desert,” reported Tom Elliot on the same post.

“I’m getting tired of writing this: 0″ in lower [Hawaiian Paradise Park],” replied David Glaser on the same post. “We need rain!!”

“Very dry here in Lava Tree park area,” reported Sammy Toney on Oct. 18 post.

The trend persisted into October after a very dry August and September for many windward areas of the island. Records for the lowest August rainfall total were broken at Glenwood, Honokaʻa, Laupāhoehoe, Mountain View, Piʻihonua and Waiākea Uka in August, according to Kevin Kodama, senior hydrologist with the National Weather Service in Honolulu who prepares the agency’s monthly Hawai’i precipitation summaries.

Windward sites continued to be mostly drier than average in September, with nearly all windward rainfall totals below 50% of average. Rainfall totals in East Hawai‘i and Kaʻū were mostly near to below average through October, Kodama reported in his most recent summary.

No October totals were available for Glenwood or Pāhoa, but the Mountain View rain gauge recorded just 48%, or 6.32 inches, of its normal October rainfall total of 13.19 inches. The most parched location on the windward side of the island was the Kahua Ranch area in North Hawai‘i, which saw just 39%, or 1.37 inches, of its normal average of 3.54 inches. Pāhala in Kaʻū got just 1.52 inches of rain last month, or 29% of its normal 5.29 inches for October.

Other locations on the windward side and in Kaʻū faired better.

The Papaikou Well rain gauge recorded the highest October rainfall total on the island of 18.79 inches, 119% of its average 15.77 inches. It also had the highest daily rainfall total on the island of 3.7 inches Oct. 5.

Hakalau saw 5.41 inches of rain last month, 112% of its average 4.83 inches. Honoka‘a got some much needed rain, recording 6.69 inches, or 122% of its average 5.48 inches. Kahuku Ranch in Kaʻū saw 5.37 inches or rain in October, 180% of its average 2.98 inches for the month, and South Point got close to normal with 2.33 inches, or 95% of its average 2.45 inches for October.

Monthly totals from the Kona slopes were mostly above average for the month.

Kohala Ranch on the leeward side of the island in North Hawai‘i recorded 2.01 inches or rain in October, a whopping 341% of its monthly average of 0.59 inches. Kealakekua saw 7.61 inches of rain last month, 176% of its average of 4.33 inches. The rain gauge at Kaloko-Honokōhau National Historical Park collected 2.37 inches of rain in October, or 162% of the 1.46 inches it normally records for the month.

Year-to-date rainfall totals on the island through the end of last month also were near to below average at most rain gauges, with the U.S. Geological Survey’s gauge at Honoli‘i Stream in East Hawai‘i taking over the lead for the highest total for the year so far with 139.73 inches. But it is only 74% of the average for the first 10 months of the year.

The state’s wet season, which runs from October through April, started with its first cold front reaching Kaua‘i on Oct. 2.

“The first cold front of the wet season usually reaches the main Hawaiian Islands around the third week of October, so it was a little early but this is not too unusual,” Kodama said in his summary. “Although weak, the front managed to reach Maui before dissipating near the Big Island.”

The cold front’s rain band produced the wettest day of the month for Kaua‘i, with 3 to 5 inches occurring mainly along the north-facing slopes. Fortunately, this enhanced rainfall did not cause significant flooding problems.

Following that cold front, a low pressure system far north of the islands displaced a subtropical high pressure ridge southward toward the state. That was the beginning of a weather pattern that put the main islands in an area of weak large-scale winds which persisted for nearly two weeks.

“Daytime onshore and upslope winds helped generate afternoon rainfall events over portions of the state, some of which were briefly heavy,” Kodama wrote, adding that minor flooding from these heavy rain events occurred on seven days in October.

Another cold front reached the state Oct. 19, bringing enhanced showers to north-facing slopes from Kauaʻi to Maui. The rain band stalled briefly over Molokai, allowing 2 to 4 inches of rain to accumulate along the north side of the island.

“Trade winds resumed on Oct. 22 and persisted through the rest of the month at mainly moderate to fresh intensities,” Kodama said in his report.

Silva-Sampaio definitely saw a difference by the end of last month. The return of the trades brought much-needed moisture to her property.

“So little by little, I got water,” she said, adding that rainbow season was back in full force about two weeks ago.

Carol Noel posted publicly at 2:26 p.m. Oct. 31 in the Puna Weather Facebook group that “someone just pulled the plug in the Great Bathtub in the Sky” on 40th Avenue in Orchidland in Puna.

“It’s been awhile since it rained like that!” replied Shauna Me Jarneski.

“Reminds me of the old days,” said Mara Mayo in reply to Noel’s post.

“I truly embrace the falling rains which feeds my catchment with goodness,” replied Jonn Norman. “It allows my landscape to blossom and allows the ginger blossoms to perfume the aire. Ahhhhhh!”

While conditions have improved in some areas now that the rainy season is underway, there are still portions of the state that remain under significant drought, with Maui County having the worst, according to Kodama.

For more details, check the National Weather Service’s Drought Information Statement.

To read Kodama’s full October precipitation summary, click here.