Catastrophic Kona Low Delivers Hawaii’s Worst Flooding In 20 Years – $1 Billion And Counting

The Synoptic Situation That Produced Hawaii’s Worst Flooding In 20 Years

The weather event that is producing Hawaii’s Worst Flooding in 20 years, during the past 12 days, is being caused by a weather system known as a Kona Low. A Kona Low is an extratropical low pressure system that is stacked up in the atmosphere (exists at upper levels and at the surface). It is positioned to the northwest or north of Hawaii. As a result, the prevailing south to southwesterly flow draws in moisture. This produces rain over the island chain.

Back To Back Kona Lows Produce Historic Flooding

There were actually two Kona Lows responsible. The first round of rains from the initial Kona Low impacted Hawaii during March 10-16, 2026. This resulted in widespread rainfall of 5″-10″. In comparison, 15″-30″ of rain fell across Maui and the Big Island. There have been locally higher reports as as much as 40″-60″ of rain in some of these areas. This occurred especially in parts of Maui (Upcountry).

In addition to producing flooding, landslides, power outages, and road closures, the initial rounds of rain left the ground very saturated, to say the least. In fact, the already soaked ground is largely responsible for the current flooding.

Round 2

A weaker, second Kona Low pressure area positioned itself northwest of Hawaii again during March 19-22. Although not as significant as the initial rounds of rain, the precipitation produced by this second low, on top of the saturated ground, produced significant, rapid runoff. It also reignited areas of flash flooding. Oahu is reporting 12″+ of rain from the second low.

A daily map of cumulative rainfall in Hawaii, for March 10-16, 2026, is located at the Hawaii Climate Data Portal.

The pressure gradient between the Kona Low and a High Pressure System located to the east of Hawaii, plus the higher momentum air brought down from aloft by the heavy rains resulted in some very high winds during March 13-15, 2026. Peak wind gust reports include 135 miles per hour (mph) at Kaiaulu Puu Waawaa (3809 feet above sea level), 110 mph on the summit of Mauna Kea (highest point in Hawaii – 13,803 feet above sea level), 108 mph at Kula, 96 mph at Waimea, 81 mph at Makapuu Beach, and 51 mph at Kalaeloa Airport. These intense winds accompanied the worst flooding Hawaii has seen in 20 years. Furthermore, they aggravated the emergency conditions.

Rainfall & Wind Reports From Hawaii’s Worst Flooding In 20 Years

Here is a list of reported rainfall amounts, in Hawaii, for March 10-16, 2026.

Here is a list of the peak wind gusts in Hawaii during March 13-15, 2026.

As of this writing (10:00 A.M. Sunday, March 22, 2026) the second Kona Low is drifting northeastward, away from Hawaii. Although some showers and thunderstorms are still occurring, a broad area of high pressure is building in. As an easterly trade wind develops, things should improve during the next 24-48 hours. The total dollar amount of this costly weather event, however, is still trending to the upside.

Some photos from the Honolulu Fire Department: This gallery documents the impact and aftermath of Hawaii’s worst flooding in 20 years.

If you need an analysis of the weather conditions that existed at a specific location and date, or dates, in Hawaii, or anywhere in the United States contact me.