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This year’s La Nina rainy season started off slow in Hawaii, but then the rain came with a vengeance—a so-called “Kona low” in early December brought as much as 14 inches in three days.

By New Year’s the weather was once again stormy. And then the faucet seemed to turn off.

Currently, nearly 80% of the Hawaiian Islands are experiencing some degree of drought, and the rest of the state is “abnormally dry.” As of January 18, no state was experiencing a drought. It was a dramatic turnaround from a winter that started with epic downpour and was forecast to be wetter than usual due to a climate phenomenon known as  La Nina .

Although climate scientists have not yet had time to analyze the numbers and pinpoint the causes, the effects are already being felt, especially on the leeward sides of the islands, where almost all of the moisture occurs in winter. The next month or so is expected to be wetter than normal, but time is running out for leeward areas.

Parts of all major islands are in “severe drought”, the second most severe of the four categories. But as the rainy season approaches, all islands could face the worst stage of “exceptional drought” 

For many Hawaii residents, the lack of rain was not a big problem. In fact, sunny days with cooler winter temperatures may seem ideal. True, there were fewer ubiquitous winter rainbows. 

But atmospheric conditions were more favorable for green flashes, when the edge of the sun briefly turns green as it sinks into the ocean, and fiery sunsets.

However, there is nothing pleasant about the lack of rain if you are a rancher. Dry weather can force ranchers to cull their herds and pay more for feed, and this dry streak comes on the heels of another last year.

“If this continues, we will likely be back in another drought emergency in 60 days,” James Robello, executive director of the USDA Maui District Farm Service Agency, said last week.

So what’s going on in the sky?

Typically,  La Nina means wetter winters in Hawaii. La Niño, which alternates with El Niño and has many complex effects around the world, occurs when sea surface temperatures near the equator fall below normal.

This winter, however, the expected La Niña pattern was disrupted when the jet stream settled north of the islands and stalled there, Kodama said. Usually the jet stream is more like a spinning garden hose, but this winter it was surprisingly still. And Hawaii remained on the dry side of the jet stream, cutting it off from rain storms.

“What’s strange is how persistent it was.”

The clear connection between La Ninas and Hawaii’s wet winters may be broken, said Pao-Shin Chu, a professor in the Department of Meteorology at the University of Hawaii at Manoa and state climatologist.

“We have global warming in the background,” he said. “This process can impact existing relationships. Global warming could stir the pot.”

The problem when it comes to rainfall is that the rainy season will soon be coming to an end. This is due to an increase in subtropical high pressure north of Hawaii, which strengthens the trade winds , but also prevents storms in northern latitudes from falling as far south as Hawaii. The windward sides of the islands may still receive a lot of rain from the trade winds, but by the time the air passes over the mountains, most of the water has been squeezed out and there is virtually nothing left on the leeward sides.

Of course, tropical storms or hurricanes in the summer and fall of 2022 could bring moisture to any part of the islands. But even then, rain may only fall over a narrow swath, Kodama said, not to mention the danger of wind and flood damage.

The weather service is predicting April will be wetter than normal , with more rain falling on the islands over the past week.

But after a long drought, Maui ranchers were already considering action, Robello said. They may have to buy bales of grass to feed their livestock. Calves can weigh 100 pounds less when sold, bringing in less money. Ranchers may be culling their herds, and due to overall poor health, breeding rates drop, meaning there will be fewer calves in the future, Robello said.

On Maui, axis deer, which, unlike deer on the mainland, feed primarily on grass, compete with livestock for food. And they can jump fences, Robello said, so the green patch the rancher hoped to save until the stormy days in August can be eaten.

Meanwhile, he said, the December flood did more harm than good as most of the water flowed away. Drier parts of Maui lack the dam and dam infrastructure needed to capture runoff from severe storms. “Our systems are not designed for this,” Robello said. 

Aerial photography in March of the ohia forest on Oahu showed tree canopies appearing less healthy than six months ago, when the canopy was lush and green, said Rob Hauff, state forester for the Department of Land and Natural Resources. The likely culprit, he said, is pests that find it easier to gain a foothold when trees are weakened by dry weather. 

Although not surveyed by the state, nayo trees on the Big Island are also susceptible to pests during drought, Hauff said. The state typically plants endangered species during the rainy season, when they have the best chance of thriving, he said, and while it’s too early to tell, the dry weather probably hasn’t helped.

Earlier this month, the State Water Resources Management Commission advised Maui residents to reduce their water use .

“Streams that are normally full of water are barely flowing,” commission deputy Kaleo Manuel said in a news release, including some whose flows were approaching the lowest flows ever recorded.

Water suppliers, especially those that rely on surface water rather than aquifers, have also felt the pressure. On Maui, this means water customers in the northern part of the country, the central valley and west Maui. Residents were urged to stop watering their landscaping and washing their cars, as well as taking shorter showers and turning off the tap while brushing their teeth.

The commission also warned of the danger of forest fires.

Even Oahu, where the water comes from an aquifer, is affected by the lack of rain. The water board has asked residents to cut their water use by 10% after increasing chloride levels were found in some of its wells, indicating a strain on the water supply. This was partly due to BWS shutting in another well to avoid sucking up water contaminated by the Navy fuel storage facility at Red Hill, but it was also due to low rainfall.

The National Drought Mitigation Center at the University of Nebraska-Lincoln offers a ground-level overview of the season’s progress , and weather observers across the country report on local conditions.

“We’ve had to water our entire subtropical landscape this week except for the lawn and podocarpus grove, which manage to stay green due to the occasional downpour,” an observer from Honokaa on the Big Island reported March 19. it rarely rains from the clouds.”

But the last few days have given some hope.

“Last week there was heavy rain that rejuvenated the lawn, trees and shrubs,” the same observer noted on Saturday. “New plantings are growing quickly.” Still, the observer noted, “only a third of the amount of rain that fell last March.”

Less rain means fewer of Hawaii’s signature rainbows, which are especially abundant in the winter because of higher humidity and because the sun traces a lower arc in the sky, said Steven Basinger, a professor of atmospheric sciences at UH Manoa. The critical angle is 42 degrees above the horizon.

“In the winter, you have a lot more time when the sun is below that critical angle,” he said.

But despite the rainbow drought, the winter was marked by more than usual numbers of fiery red sunsets and flashes of green, he said, “providing the spiritual sustenance we all expect in Hawaii.”

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