Overview of the intense rainfall event over Oahu on February 21, 2026

A vigorous short-wave trough combined with orographic lift from the Koolau Mountain Range and sufficient low level moisture produced a nearly stationary band of heavy rain and thunderstorms over the Koolau Mountains on Saturday, February 21st. The heaviest rain occurred between Maunawili and Hauula for around 4 to 6 hours that morning, with intense rainfall rates of 2 to 4 inches per hour and brief periods of over 6 inches per hour observed. This led to rapid rises in area streams and overwhelmed storm water channels and drains.

Significant flash flooding occurred along both the windward and leeward sides of the mountain range, with the most notable and widespread impacts in the Kaneohe, Waiahole, Waikane, and North Shore areas. Several roads were closed, including the Likelike Highway off-ramp from the Kaneohe-bound H-3 Freeway. Water from overflowed streams entered several homes and vehicles in Kaneohe and inundated the Otake Camp area of Waialua.

Note: The previous 24-hour precipitation report summary included amounts as of 5 PM HST on the 21st, and as such, included rainfall from the previous evening, so the values may differ from the ones listed below. Midnight to midnight was chosen for this summary to capture the main period of widespread heavy rainfall. Data is preliminary and for information purposes only.

Highest 24-hour Rainfall Totals (midnight HST Feb 21st to midnight HST Feb 22nd) for the island of Oahu...

Location	Amount (inches)
Luluku (NWS/13016)	25.10
Moanalua RG (USGS)	17.51
Poamoho RG1 (USGS)	16.32
Heeia NERR	11.25
Tunnel RG (USGS)	9.04
St. Stephens (NWS/13006)	8.74
Maunawili (NWS/13008)	6.46
Kamananui Stream (USGS)	6.31
Oahu Forest NWR (USFWS)	6.07
Kahana (USGS)	6.02

Significant Rainfall Rates Across Oahu on February 21st...

Luluku (NWS/13016):	17.07 inches in 6 hours	13.01 inches in 3 hours
Moanalua RG (USGS):	13.44 inches in 6 hours	12.49 inches in 3 hours
Poamoho RG1 (USGS):	13.09 inches in 6 hours	8.10 inches in 3 hours