Drought in Hawaii fuels rare wildfires in November


You don’t often expect to hear “Hawaii” and “fire danger” in the same sentence, but concerns about wildfires have been very real in the state of Aloha in recent days. A prolonged drought dries up the landscape and has a noticeable impact on agriculture and ecosystems.

More than half of Hawaii is currently experiencing unusually dry conditions, with 30 percent facing a moderate or worse drought. That’s according to the federal government’s Drought Monitor, which provides detailed weekly summaries of drought intensity and impact across the United States.

More than 80 percent of the US is facing worrying drought conditions

The Drought Monitor even warns that in the few remote places that experience extreme drought, “wild donkeys are migrating to settled areas” and that “trees are dry and dropping leaves.” That further exacerbates the risk of wildfires, something the local office of the National Weather Service in Honolulu is increasingly concerned about.

“A combination of high winds, low relative humidity and warm temperatures can contribute to extreme fire behavior,” it warned Monday after issuing a red flag warning. Such warnings do not predict wildfires starting, but rather convey that any spark can quickly become a raging inferno.

Monday’s red flag warning was Hawaii’s first in November since 2012.

Red flag warnings are issued more frequently in the late summer months of August and September when the landscape tends to become drier after the summer dry season.

According to the Hawaii Wildfire Management Organization, “each year, 0.5 percent of Hawaii’s total land area burns, equal to or greater than the percentage burned of any other U.S. state.”

Autumn rains usually end the summer dry season, but they have been unreliable this year. So far, Honolulu has had just 0.09 inches of rain in November, about an inch and a half behind the average, and October has only half its normal rainfall.

Since the beginning of the year, Honolulu has gained 9.8 inches compared to an average of 13.6; Although it represents a 28 percent deficit, it’s nowhere near as bad as it was in 1998, when it had fallen just 3.34 inches by mid-to-late November.

Temperatures are also highest in late summer, which means the greatest evaporation. This dries out the landscape, and rapid drying occurs between late July and early October. The drought peaked in early September this year when 94 percent of the state was affected.

Much of Hawaii remained in drought until late October, when beneficial rains arrived. In the meantime, however, dry weather has returned.

“Following drought-mitigating rains, Hawaii turned slightly drier amid a predominantly trade wind regime,” the drought monitor wrote. “As a result, no further improvement was seen in Hawaii after 9 consecutive weeks of drought coverage reduction.”

The lack of precipitation this year has resulted in low relative humidity, falling below 45 percent at times. While 45 percent is humid by California standards, it’s fairly dry on a tropical island chain like Hawaii, which is about 20 degrees north latitude. In recent days, a strong clockwise high-pressure system north of the archipelago has swept dry air southwards while creating gusty winds.

Aside from the obvious problems of wildfire risk, the ongoing drought is also impacting agriculture and the ecosystem. In August, about 8 percent of Maui was classified as having an “extraordinary” drought — the highest level.

SFGate.com, an online news publisher in San Francisco, reported that the lack of rain and past pineapple-growing practices in the mountains of western Maui have made it more difficult to withhold and conserve water, affecting reservoir levels and ranchers.

On Molokai and Maui, wild deer are encroaching on farmland and competing with livestock for resources, in part because of the arid conditions. Donkeys also migrate to populated areas.

“Despite continued efforts, the deer population has swelled to approximately 60,000 or more, which the environment in Maui County cannot sustain,” said a Nov. 18 proclamation by Hawaii Governor David Ige (D). This is the governor’s fifth consecutive proclamation regarding the deer crisis, with special measures remaining in effect through January 17.

“This includes fencing off axis deer, culling deer to sustainable levels, clearing vegetation along fence lines, and erecting and/or reinforcing fence lines to keep axis deer off roads, airports and airstrips,” the document said .

The National Weather Service’s Climate Prediction Center winter outlook calls for a gradual improvement in the state’s drought conditions.

Hawaii joins large portions of the Lower 48, which are also currently experiencing significant drought. The Nov. 15 drought monitor update showed that 82 percent of the contiguous U.S. is experiencing unusually dry or drought conditions — nearly the highest percentage on record (85 percent as of Nov. 1 of this year).

A July study in the Journal of Climate found that drought conditions in Hawaii, which have prevailed for much of the past decade, are among the worst on record. However, it was not possible to link the drought to long-term climate change because computer models evaluating its drivers failed to detect human impact.

“[N]ot every event has an obvious and simple “first cause” – natural weather mechanisms have proven powerful to produce extreme events and trends over considerable time periods,” the National Oceanic and Atmospheric Administration’s climate program office wrote in a news release.

The US government’s fourth national climate assessment, released in 2018, warned that rising temperatures will increase the risk of extreme drought and flooding in Pacific island communities in the future.

Jason Samenow contributed to this report.