Heavy Rains Trigger Landslides and School Closures Across Hawaii

Hawaii is no stranger to rain. The islands are home to some of the wettest places on Earth. But when a powerful Kona low stalled over the archipelago in mid-March 2026 — dumping more than 16 inches of rain on Maui summits, knocking out power to over 130,000 customers, and pushing a century-old dam toward failure — it laid bare an uncomfortable truth: the infrastructure holding Hawaii together was built for a climate that no longer exists.

A Week the Islands Shut Down

The trouble began before the storm even arrived. On March 9, Governor Josh Green issued an emergency proclamation — effective through March 18 — in anticipation of the Kona low system bearing down on the state [1]. It was a preemptive move, and an unusual one: the proclamation covered all four counties and unlocked emergency resources before a single raindrop had fallen.

By Thursday, March 12, bands of heavy rain and thunderstorms were sweeping across the islands. The National Weather Service issued flash flood warnings for Oahu and Kauai as rainfall rates hit 1 to 2 inches per hour [2]. Schools were the first domino to fall. The Hawaii Department of Education announced all public schools and HIDOE offices statewide would close on Friday, March 13 [3]. The University of Hawaii followed suit, shuttering campuses on Kauai, Oahu, and Maui County [4]. State agencies and Honolulu city offices closed for non-essential business.

Then Friday arrived, and the storm's full fury was unleashed.

Deluge by the Numbers

Wind gusts exceeding 100 mph lashed the islands — the National Weather Service recorded a 126 km/h (78 mph) gust on Oahu, with even more extreme readings at higher elevations [5]. The rain was relentless. Mount Kaala on Oahu recorded 12.63 inches; Maunawili saw 10.48 inches; a Maui summit gauge measured 16.31 inches [6]. On Hawaii Island, radar showed rainfall rates of 1 to 2 inches per hour pounding the Puna and Kau districts, turning highways into rivers and forcing the closure of Highway 11 at Kawa Flats [7].

Source: National Weather Service Honolulu / Honolulu Civil Beat

Data as of Mar 14, 2026CSV

The cumulative effect was devastating. Across the state, transportation crews responded to roughly 28 storm-related incidents — 15 large tree falls (some with trunks up to 10 feet in diameter), eight roadway flooding events, and several landslides and debris flows [6]. On Oahu, a landslide closed Pacific Heights Road near Haili Road. Another rendered Auloa Road impassable near the Pali Highway. On Molokai, Kamehameha V Highway near Kawela Gulch was blocked entirely [8]. In Waikiki — the state's tourism engine — Kalia Road near the Outrigger Reef and Halekulani hotels flooded while a massive tree crashed across Kalakaua Avenue, blocking nearly the entire roadway and damaging a streetlight [9].

130,000 in the Dark

The power grid buckled. By Friday evening, approximately 132,000 Hawaiian Electric customers were without electricity — roughly 123,000 on Oahu alone, with 5,000 in Maui County and 3,600 on Hawaii Island [10]. The most critical damage involved two of the three high-voltage transmission lines carrying power over the Koolau Range to Hawaii Kai and East Honolulu. A specialized helicopter had to be dispatched Saturday morning to inspect the ridgeline damage, and Hawaiian Electric warned that restoration could take "anywhere from several hours to days or longer" [11].

The utility urged customers to prepare for extended outages, noting that crews could only work when weather conditions were safe [10]. On Maui, the Skyline transit service was temporarily suspended. Maui County ended all bus routes by 7 p.m. Friday due to road closures and flooding [6].

A Dam on the Edge

Perhaps the most alarming development was the situation at Wahiawa Dam on Oahu's North Shore. As rainwater poured into the reservoir, levels climbed to 82.8 feet — approaching the 85-foot threshold that would trigger mandatory evacuations. Dam failure occurs at 90 feet [12]. Governor Green called it "his biggest concern" [6].

The Honolulu Department of Emergency Management issued a "get ready to go" notice to residents of Waialua and Haleiwa, warning that a breach could send water downstream rapidly and cause "catastrophic flooding" [12]. Emergency Management Director Randall Collins told reporters the situation "remained uncertain" as long as rain continued to fall [13].

The dam held. By Saturday morning, water levels had stabilized at 81.9 feet — down nearly a foot from the previous night — and the evacuation notice was lifted [14]. But the hours of uncertainty underscored how a single aging piece of infrastructure could threaten entire communities during extreme weather.

The Sewage No One Talks About

Beyond the visible damage, the storm triggered a cascade of wastewater failures. Heavy rain overwhelmed sewer systems across Oahu and Kauai, causing multiple sewage overflows [15]. The Wahiawa Wastewater Treatment Plant's storage tanks reached capacity around 12:44 p.m. Friday, spilling into Lake Wilson. The Kaneohe Tunnel Influent Facility overflowed into Kawa Stream. The Kailua Regional Wastewater Treatment Plant's primary clarifiers were overwhelmed, discharging into Nuupia Pond. The Ahuimanu Preliminary Treatment Facility also spilled wastewater into a nearby stream [15].

City officials said crews were responding to the sites but were still calculating the total volume of wastewater released. The Hawaii Department of Health issued water advisories for affected areas on both Oahu and Kauai [16].

Not the First Storm — and Not the Last

What makes this Kona low particularly alarming is the context. Just five weeks earlier, in early February, another powerful storm hammered the islands, closing Hana Highway on Maui with a massive landslide at Mile Marker 14, dumping 21.84 inches of rain at the Waiakamoi Treeline on Haleakala in 24 hours, and knocking out power to tens of thousands [17]. That storm also prompted Governor Green to issue an emergency proclamation and close state offices and schools [18].

Two major Kona lows within five weeks is not typical. Hawaii generally experiences two to three Kona storms per year, concentrated between November and March [19]. But this season has compressed that frequency dramatically, and the back-to-back events meant the ground was already saturated when the March storm arrived — amplifying landslide risk and reducing the soil's capacity to absorb rainfall.

Built for Another Era

The deeper story is one of infrastructure designed for a world that no longer exists. State Department of Transportation Director Ed Sniffen told the Honolulu Star-Advertiser that much of Hawaii's drainage systems, bridges, and roadways were built in the 1960s and sized for weather patterns and development levels that have since changed dramatically [20].

"Everything was built in the '60s, and everything was sized for that," Sniffen explained. As Oahu urbanized, adding pavement and buildings, water runoff increased far beyond what the original drainage systems were designed to handle — but those systems were never upgraded to match [20].

The math is sobering. What engineers historically considered a "100-year storm" — one with a 1% chance of occurring in any given year — is now happening with startling regularity. Sniffen noted that the current storm qualified as a 100-year event, yet there had been another one just three weeks prior [20]. Future infrastructure, he said, would need to be built to withstand 200- or even 250-year storm events, requiring "substantially larger and more expensive drainage systems and bridge openings" [20].

Climate Change and the Kona Low

The scientific picture is complex. Earlier research suggested Kona lows might actually become less frequent under climate change [19]. But those studies predate the recent acceleration of extreme weather events. What the data increasingly shows is that even if individual storm frequency changes modestly, the storms that do form are more intense — fueled by warmer ocean temperatures and carrying more moisture.

Hawaii's sea surface temperatures have risen measurably over recent decades, and a 2017 University of Hawaii study warned that much of Honolulu and Waikiki is vulnerable to groundwater inundation as sea levels rise [21] — a compounding factor that makes surface flooding even worse during heavy rain events.

The February and March 2026 storms, taken together, represent a stress test that Hawaii's infrastructure largely failed. No fatalities were reported — a credit to the emergency management system and the decision to close schools and offices preemptively — but the cascading failures across power, transportation, water, and wastewater systems revealed fragilities that will only worsen as climate change accelerates.

Rescues and Response

Emergency crews performed multiple rescues during the storm's peak. On Oahu, responders pulled four people and a dog from beneath a Honolulu bridge after rising floodwaters trapped them [6]. In another incident, nine people were rescued from under a bridge near Kaimuki High School when flood water nearly swept them away [22]. In Waialua, residents of Otake Camp were ordered to evacuate to Waialua High and Intermediate School as water levels rose [6].

Governor Green praised the coordinated response between state and county agencies but acknowledged the scale of the challenge. Emergency shelters were opened across the islands, and the National Guard was placed on standby [1].

What Comes Next

The Kona low was forecast to continue impacting the islands through the weekend of March 15-16 before lifting on Monday [7]. But even after the skies clear, the cleanup will take days, and power restoration in the hardest-hit areas of East Honolulu and Windward Oahu could extend beyond that [11].

The larger reckoning is just beginning. Hawaii faces a multi-billion-dollar question: how to retrofit 1960s-era infrastructure for 21st-century storms on islands where geography makes conventional solutions — bigger drainage pipes, elevated roads — extraordinarily expensive and sometimes physically impossible. Low-lying highway sections near Waiahole, Waikane, and River Street on Oahu flood persistently because the underlying geography cannot be altered without potentially redirecting floodwaters to surrounding communities [20].

For now, the islands are drying out. Schools reopened. Power is returning. But the saturated ground, the straining dam, the sewage in the streams, and the landslides blocking highways tell a story that will repeat — with increasing frequency and severity — until Hawaii confronts the gap between the infrastructure it has and the climate it now lives in.