Hawaii governor estimates over USD 1 billion in storm damages as severe flooding continues across Oʻahu
Storm damage in Hawaii could exceed USD 1 billion as severe flooding from a Kona low affects Oʻahu on March 20–21, 2026, forcing about 5 500 residents to evacuate and triggering emergency warnings over the imminent risk of failure at Wahiawā Dam.
Wahiawā Dam rose to dangerously high levels on Friday, March 20, 2026, even as water flowed over the spillway at a rate of about 5 700 L/min (1 500 gallons per minute). Credit: Honolulu Fire Department
Severe flooding continues across Oʻahu, Hawaii, as two slow-moving low-pressure systems associated with a Kona low pattern sustain heavy rainfall over the island, producing dangerous conditions, widespread evacuations, and an ongoing dam emergency.
The most affected areas include the North Shore communities of Haleiwa, Waialua, and Wahiawā, where floodwaters have inundated roads, homes, and low-lying areas.
Hawaii Governor Josh Green estimated that storm damage across Hawaii could exceed USD 1 billion. Emergency management authorities warned of an imminent failure of Wahiawa Dam, triggering Flash Flood Warnings with Emergency Alert System (EAS) activation for areas downstream along the Kaukonahua Stream.
Flooding is affecting downstream areas, including Waialua and Haleiwa, with warnings indicating continued risk to communities along the Kaukonahua Stream.
More than 230 people were rescued from flooding across Oʻahu on March 20, according to emergency officials, with Honolulu Mayor Rick Blangiardi saying 233 people needed rescue. Rescue operations included responses in Waialua and Wahiawā, while additional evacuations were carried out in ʻEwa Beach due to flood risk.
The storm produced hourly rainfall rates of 50–75 mm (2–3 inches). Additional widespread rainfall totals of 75–200 mm (3–8 inches) are forecast statewide, with localized higher amounts possible where convective bands develop.
Rainfall totals of 50–150 mm (2–6 inches) were recorded in parts of Oʻahu over a 6-hour period, with a maximum of 218 mm (8.58 inches) at Wahiawā. This contributed to rapid runoff, rising stream levels, and flooding across multiple areas.
Flooding has submerged streets, highways, properties, and other low-lying areas, and landslides remain possible in steep terrain, disrupting transport across O’ahu.
Emergency response operations are ongoing, with shelters activated and evacuation orders remaining in place for areas at highest risk, particularly downstream of Wahiawa Dam. Authorities continue to monitor conditions as additional rainfall is expected to affect the island.
The severe weather is being driven by two low-pressure systems moving slowly northeastward across the region, supported by an upper-level trough and subtropical jet stream. This setup is generating repeated bands of heavy showers and thunderstorms, increasing the threat of flash flooding across the Hawaiian Islands.
Forecast guidance indicates that periods of moderate to heavy rainfall and thunderstorms will continue through the weekend, with the flood threat persisting and gradually shifting eastward across the island chain. A Flood Watch remains in effect statewide through Sunday, and conditions are described as a dangerous, life-threatening weather pattern.
Flash Flood Warnings remain active, with authorities warning of flooding in streams, rivers, roads, and low-lying areas. Residents in affected areas are urged to avoid floodwaters and comply with evacuation orders as emergency conditions continue.
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References:
1 Area Forecast Discussion for Hawaii – NWS – March 20, 2026
2 Flash Flood Warning – NWS – March 20, 2026
I am an Assistant Editor and Severe Weather & Science Journalist at The Watchers, specializing in real-time severe weather coverage, geophysical event reporting, and research-driven scientific analysis. You can reach me at rishav(at)watchers(.)news.
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