Maui County drought alleviates after one of the wettest Decembers in half century

One of the wettest Decembers in the last half century quenched extreme drought in Maui County, which was suffering from the worst conditions in the state.

In fact, a couple Maui areas set all-time rainfall records for the month, according to a report released today by Kevin Kodama, senior service hydrologist for the National Weather Service in Honolulu.

Current conditions show no areas of “exceptional,” “extreme,” “severe” or even “moderate” drought in Maui County and the rest of the state, according to the U.S. Drought Monitor. 

A month ago, Maui County was riddled with all five levels of drought, ranging from “abnormally dry,” the least intense, to “exceptional,” the most intense. 

Kodama had called Maui County’s drought conditions worse than the previous year and the most severe in the state. Local ranchers and farmers had been reporting financial losses and other negative impacts.

Last month took a different turn, though.

“After a slow start to the 2021-2022 Hawaiian Islands wet season, with dry overall conditions in October and November, the month of December appears to have made up for lost ground,” Kodama said in the report.

Records for December rain totals were broken at Haʻikū and Lahainaluna gauges. 

Molokaʻi Airport had its highest December total since 1996. Also, Kaunakakai Mauka, Kula Branch Station, Kīhei No. 2, Mahinahina, Makapulapai, Puʻu Kukui and ʻUlupalakua Ranch had their highest December totals since 2007, the report said.

Most of Maui County’s rainfall totals were above average for the month of December. United States Geological Survey’s Puʻu Kukui gauge had the highest monthly total of 52.10 inches, which is 175% of its average. 

The highest daily total of 7.56 inches Dec. 22 came from the USGS rain gauge at West Wailuaiki Stream.

Most rainfall totals for 2021 were nearly above average across Maui County. The rain gauge at West Wailuaiki Stream had the highest annual total of 287.55 inches, which was 128% of average. This was followed by Puʻu Kukui’s 281.01 inches, which was 77% of average.

Although additional analysis is needed, the Dec. 5 to 8 kona low appears to have been one of the strongest to affect Hawaiʻi in the last 50 years, Kodama said. The impacts are similar to kona low events in January 1980, December 1987 and December 2008.

Rainfall pummeled Hawaiʻi when a kona low marched across the islands early last month, sparking flooding, road closures and other serious infrastructure damage.

Persistent, heavy rain started over Maui on the afternoon of Dec. 5. Soon, large flash floods filled the normally dry gulches west of Kaupō and closed Piʻilani Highway. Flooding poured through homes and washed away vehicles in Maui Meadows. Kīhei and Kula suffered property damage, road closures and other impacts as well.

By the afternoon and evening of Dec. 6, thunderstorms and heavy rainfall moved over Oʻahu.

Kona low is not capitalized because “kona” refers to the adjective, “leeward,” in the Hawaiian language; the usage is consistent with several research papers covering subtropical cyclones in the central North Pacific, Kodama said.

Overall, the month is “one of the wettest Decembers in the last 50 years,” the report said.

December ended with the return of southeasterly to southerly winds over the state in response to a low pressure system to the west of Kauaʻi.

Periods of heavy rainfall moving over the Hanalei River basin resulted in the closure of Kūhiō Highway near the Hanalei River Bridge for several hours Dec. 31. Passing heavy showers also produced minor flooding on Oʻahu, Molokaʻi, Maui and the Big Island.