A big and doubtlessly harmful moisture surge is underway throughout the Hawaiian Islands this weekend as a tropical plume using the periphery of a strengthening high-pressure ridge drives precipitable water values approaching 1.5 to 1.7 inches or increased throughout the state, based on the NWS Climate Prediction Middle.
The NWS Honolulu Forecast Workplace up to date its alerts Sunday morning, warning that durations of heavy rain are potential by way of the weekend, with some enhanced bathe exercise doubtless throughout all islands the place terrain-induced convergence and leeward results can intensify rainfall dramatically.
The company warned instantly: “It doesn’t need to be raining at your location for flash flooding to happen. If you happen to discover indicators of heavy rain or thunderstorms upslope, transfer rapidly away from flood-prone areas.” Streams, valleys, and coastal low factors throughout all islands stay the areas of best concern.
A State Already Battered by a Historic Flood Season
The moisture surge arrives in opposition to a backdrop of what has already been a catastrophic spring for Hawaii. Again-to-back Kona low strain programs struck in March 2026, delivering among the worst flooding the state has seen in a long time, with the NWS reporting rainfall totals of 5 to 10 inches throughout the state between March 11 and 15, with some areas recording greater than 30 inches. Governor Josh Inexperienced described it because the worst flooding Hawaii had seen in 20 years, with estimated damages approaching $1 billion.
Simply days in the past, on Could 15, lightning strikes lower energy to 37,000 prospects on Oahu as heavy rain pounded the island, with the Honolulu Star-Advertiser reporting radar-indicated rainfall charges of two to three inches per hour over the Koolau Mountains — charges able to triggering flash flooding inside minutes on already-saturated soils.
What Residents Ought to Do Now
Soils throughout a number of islands stay saturated from weeks of above-average rainfall, that means even reasonable rainfall totals can set off harmful and fast stream rises.
The Hawaii Emergency Administration Company urges residents to keep away from all streams and low-lying areas throughout rain occasions, by no means try to cross flooded roadways, and join native emergency alerts at prepared.hawaii.gov/alerts. Landslides stay an elevated risk in steep terrain throughout Maui, the Huge Island, and the Koolau Vary on Oahu.
