A slow-moving Kona low has brought heavy rainfall to parts of Hawaii over the past five days, with the National Weather Service in Honolulu documenting multiple daily rainfall records at individual stations, including some benchmarks dating back to 1951. Preliminary readings through March 15, 2026, compiled by NWS Honolulu, show several stations on Oahu, Maui, and the Big Island exceeding prior records. With the system still lingering and additional rain possible, Governor Josh Green has issued a second emergency proclamation, and flood risks remain elevated for communities already saturated by days of downpours.
Five Days of Rain Rewrite the Record Books
The National Weather Service office in Honolulu released preliminary totals measured through 10 a.m. HST on March 15, 2026. The data covers station-by-station readings across Oahu, Maui, and the Big Island, and the numbers tell a consistent story: accumulations far exceeded what forecasters initially projected when the Kona low first stalled over the island chain.
What makes this event historically significant is the specific records it erased. At Kahului Airport on Maui, gauges recorded 1.01 inches on March 11, 2026, well above the prior daily maximum of 0.53 inches, according to record reports from NWS Honolulu. That old mark had persisted for decades. The Kahului break is just one entry on a growing list of shattered benchmarks documented in the office’s record event tracking system, which catalogs each new record alongside the date, the amount, and the prior high it replaced.
For residents, the distinction between a heavy rain event and a record-setting one is not academic. When rainfall approaches or exceeds historical records, drainage systems and waterways can be stressed, and localized flooding can develop quickly. Streams and culverts sized for typical historical conditions may be overwhelmed during unusually intense downpours. In communities across the islands, the prolonged rainfall has heightened concerns about flooding where soils and drainage are already saturated.
1951 and 2006: The Benchmarks That Fell
Many of the records broken during this Kona low trace back to March 1951, a month that left a deep imprint on Hawaiian climate data. NWS Honolulu maintains archived rainfall guidance for Honolulu and other stations, and those tools confirm that 1951 set benchmarks still referenced in official climate tables. The federal Climate Data Online portal, available through the National Centers for Environmental Information at NCEI records, provides quality-controlled historical precipitation data from that era for stations including Honolulu International Airport and Lihue Airport, allowing direct comparison with current readings.
The 1951 records were not untouchable. A prolonged wet period from February 19 to April 2, 2006, broke several of them during weeks of sustained rainfall across the state. An NWS Honolulu event summary of that 2006 episode explicitly noted a similar pattern to March 1951, which “held some rainfall records that were broken in this event.” That analysis is relevant now because the March 2026 Kona low shares key characteristics with both predecessors: a stalled low-pressure system feeding tropical moisture into the islands over an extended period rather than passing through quickly.
The pattern matters because it challenges a common assumption in popular weather coverage, which tends to treat each record-breaking storm as a standalone anomaly. In reality, the 1951, 2006, and 2026 events share a recognizable atmospheric setup. For hydrologists and emergency planners, the recurrence of this pattern is a reminder that prolonged Kona lows can produce extreme rainfall totals, and that flood mitigation plans are often evaluated against historical benchmarks.
Governor Green Extends Emergency Powers
The scale of the storm prompted Governor Green to issue a second proclamation relating to the March 2026 Kona low, extending emergency measures first activated as the system intensified. The proclamation, hosted by the Hawaii Emergency Management Agency, expands the state’s ability to mobilize resources and direct aid to affected areas.
The second proclamation extends the state’s emergency posture as the Kona low continues. For residents in flood-prone areas, an emergency proclamation can support state coordination and resource mobilization while hazardous weather is ongoing. Issuing it while the storm is still active is intended to help agencies respond quickly if conditions worsen or additional heavy rain develops.
State and county agencies can use the expanded authority under an emergency proclamation to coordinate response activities and direct resources where needed. With the storm still producing impacts in some areas, officials are focused on reducing response times and maintaining access to critical routes and services.
Why the Threat Is Not Over
The NWS Honolulu record index continues to update as new data comes in, and the agency’s preliminary precipitation statement explicitly covers only totals through the morning of March 15. The Kona low has not yet exited the region, and saturated soils across all major islands mean that even moderate additional rainfall can trigger flash floods and landslides.
This is the core danger for the days ahead. Ground that has absorbed record-setting moisture loses its ability to soak up more. Water that would normally percolate into volcanic soil instead runs off immediately, turning small streams into fast-moving channels. Roads built on hillsides become vulnerable to washouts, and neighborhoods in low-lying areas face standing water that can persist for days after the rain stops. Even if rainfall rates decrease from their peak, the combination of saturated terrain and lingering showers can keep rivers high and slopes unstable.
Emergency managers are emphasizing that the end of the heaviest rain bands does not mark the end of risk. Debris carried by earlier floods can clog culverts and drainage ditches, making subsequent, smaller storms more hazardous than they would otherwise be. Residents returning to clean up mud and water damage may find themselves in harm’s way if another burst of rain sends runoff back through the same channels. Authorities are urging people to heed road closure signs, avoid driving through moving water, and stay alert to rapidly changing forecasts.
What Comes Next for Forecasting and Preparedness
The Commerce Department, which oversees NOAA and its weather forecasting agencies, plays a central role in interpreting events like this Kona low for long-term planning. As NWS Honolulu refines its preliminary numbers and updates official climate records, those datasets will feed into broader federal assessments of extreme precipitation trends across the Pacific.
For Hawaii, the March 2026 storm will likely become a new reference point in discussions about resilient infrastructure. Engineers and planners now have another concrete example of how much rain can fall in a short window when a Kona low stalls, and how those totals compare with the mid-century events that shaped existing design standards. By pairing updated observational records with historical archives from 1951 and 2006, state and county agencies can better gauge whether current drainage and slope-stability planning aligns with the range of extremes reflected in the observational record.
In the meantime, the focus remains on getting through the current event. With records still being tallied and the Kona low only slowly weakening, Hawaii’s experience over these five days is a reminder that for island communities, the line between a strong storm and a historic disaster can be crossed in a single saturated week.
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*This article was researched with the help of AI, with human editors creating the final content.
