Insured losses from a pair of powerful Kona storms that hit Hawaii in March are expected to reach at least $1 billion, according to Aon, adding to what is shaping up as a costly month for US property insurers.
The March events come on top of back-to-back billion‑dollar severe convective storm (SCS) outbreaks on the mainland, further stretching catastrophe budgets.
Aon said densely populated Oahu, particularly areas north of Honolulu, suffered "extreme devastation from severe flash flooding and landslides, mainly during the overnight hours on March 19-20." According to a report from BestWire, countless vehicles were swept away and hundreds of homes were inundated or knocked off their foundations, while schools, hospitals and airports sustained damage. Local officials described the flooding as the worst in more than 20 years, with thousands of residents ordered to evacuate and many still without power days after the storm.
The city and county of Honolulu, which covers Oahu and outlying northwest islands, accounted for nearly 999,000 of Hawaii’s 1.4 million residents in 2024, concentrating much of the state’s human and economic exposure in the areas hardest hit. Hawaii Island and Maui were struck earlier by a first Kona low between March 10 and 15, sustaining similar but somewhat less severe damage. State officials have estimated at least $9.4 million in agricultural losses, with coffee and other high‑value crops heavily affected.
In a formal request for a presidential disaster declaration, Governor Josh Green said preliminary assessments indicate more than $400 million in damage from the first storm alone, with total economic losses from both systems expected to top $1 billion.
For mainland carriers, the Hawaii flooding comes during an already active stretch for secondary perils. Market estimates suggest that March SCS outbreaks are likely to be at least the second and third US billion‑dollar convective storm events of 2026, continuing a pattern in which SCS and flood consistently generate multibillion‑dollar insured losses even in relatively quiet hurricane seasons.
Aon’s latest climate and catastrophe reporting showed that SCS has now surpassed tropical cyclone as the costliest insured peril of the 21st century, with 2025 alone seeing tens of billions of dollars in global SCS insured losses and a long‑term trend of rising event severity.
For global property‑cat writers, the Hawaii events underline how regionally focused flood and rain‑on‑snow episodes can stack on top of continental SCS to drive aggregate losses, complicating how they allocate catastrophe capacity and price secondary‑peril aggregates.
From a flood insurance standpoint, the March events are again exposing Hawaii’s coverage gap. FEMA data indicated that only a modest share of homes in the state carry National Flood Insurance Program (NFIP) policies, and recent analysis suggested that, even when private policies are included, only a small fraction of households have any form of flood coverage.
Meanwhile, a 2024 survey by the city and county of Honolulu found that most Oahu residents did not realize standard homeowners' and renters' policies exclude flood, and only a minority understood that hurricane insurance does not cover standing water from storms. That level of awareness, combined with relatively low NFIP penetration, leaves many households reliant on federal disaster aid, state programs or personal savings when off‑floodplain flooding occurs, according to the report.
The March flooding also comes amid ongoing debate over NFIP’s Risk Rating 2.0 reforms, which are raising premiums for many coastal policyholders while the program remains heavily indebted to the US Treasury. The combination of low take‑up, NFIP uncertainty and heightened flood risk raises familiar questions about how aggressively to grow private flood offerings versus relying on federal backstops in markets like Hawaii, where localized cloudbursts and Kona lows can produce catastrophic damage far from mapped floodplains.
Climatologists noted that Kona lows - cold‑core systems that stall to the west or southwest of the islands and funnel deep tropical moisture over steep terrain - have long been among Hawaii’s most damaging winter hazards. What is changing is the backdrop, with warmer sea‑surface temperatures and a moister atmosphere increasing the potential for intense, localized downpours, as seen in the rainfall rates recorded during the March storms.
According to the report, the latest events add to the evidence that traditional hazard maps and historical loss records may understate inland flood risk in island and coastal settings. In the near term, the March Kona storms are likely to feature in 2027 US property‑cat renewal discussions around Hawaii’s all‑perils programs, modeled Kona‑low scenarios and the pricing of both NFIP “write‑your‑own” arrangements and private flood treaties covering the state.
