Two Kona low storms have hit Hawaiʻi over the last month, creating serious flood conditions in many parts of the state.
University of Hawaiʻi Climate Data Portal Mesonet Director Thomas Giambelluca explained what created those conditions and what it could mean for future storms.
"Kona storms do happen in Hawaiʻi. Usually, every winter we get at least some, but it does vary a lot from year to year," he said. "The thing that distinguishes them is that they become cut off from the upper-level westerly winds that normally steer winter-type storms."
He explained that when those upper-level westerly winds move toward the equator and up toward the poles, they form a trough that can become so elongated that an eddy — a circular current of water — can spin off the end of it.
"That's one of the reasons that Kona storms can give us a lot of rain, because they don't move very fast. And so that's kind of what happened last week and is happening now with this sequence of two Kona storms," Giambelluca said.
Kona storms are a strong determinant of annual rainfall in the state — and 2025 was the second driest year in over a century in Hawaiʻi.
The recent Kona lows could change that for 2026, which have created significant amounts of rain.
Whether or not climate change is to blame for the storms, there’s no strong consensus.
But Giambelluca explained that it does fit one scenario they are tracking, where the conditions are generally becoming drier, but the storms that do occur are more intense.
"Even if we're getting drier on average over time, which we seem to be doing, we can have these bigger extremes than we've had in the past," he said. "And that is consistent with how we think the atmosphere is changing due to climate change."
Giambelluca and his team continue to operate and collect data from a statewide climate monitoring network.
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