Flash Flood Warning Hawaii | Effective 03/20/2026 10:43

FFWHFO The National Weather Service in Honolulu has extended the * Flash Flood Warning for... The island of Oahu in Honolulu County * Until 1100 AM HST. * At 743 AM HST, emergency management reported widespread life-threatening flash flooding effects continuing across northern Oahu, particularly in the Haleiwa and Waialua areas. Although rainfall rates have temporarily decreased, significant runoff continues to produce high water levels, including the Wahiawa Reservoir which continues to rise. Additional bands of heavy rainfall moving in from the southwest will continue over the area throughout the day, which could lead to renewed rises in water levels and worsening flooding conditions. The Wahiawa Reservoir (Lake Wilson) remains elevated, with water levels continuing to rise from runoff, despite a break in the heavy rainfall. Additional rises in this reservoir could further exacerbate downstream flooding along the streams, particularly near Otake Camp in Waialua. For the windward side of Oahu, periods of heavy showers will continue to develop and move through, with rainfall rates of 1 to 2 inches per hour. Water levels in the streams remain high, especially in the Waiahole, Waikane, and Kahana streams. Runoff impacting vulnerable low lying areas and roads will continue through the morning hours. This is a FLASH FLOOD EMERGENCY for Northern Oahu. This is a PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER GROUND NOW! HAZARD...Heavy rain producing life threatening flash flooding. SOURCE...Stream Gauges. IMPACT...Severe flooding in drainages, streams, rivers, roads, properties, and other low lying areas. Numerous public road closures expected, as well as landslides in steep terrain. Significant property damage expected to homes and other properties in low lying areas. * Some locations that will experience flash flooding include... northern half of Oahu, along and north of a line from Waianae Valley to Mililani Mauka to Waiahole.