Marine Weather and Tide Forecast for Kekaha, HI

DISCUSSION
Issued at 840 PM HST Tue Mar 17 2026

This evening, a band of showers with predominately light to moderate rain rates is seen on radar and satellite imagery moving across portions of east Maui and the Big Island. These showers are associated with a low-level trough that is moving through this evening. As the trough moves farther away from Maui, expect improving conditions there, though latest hi-res guidance depicts lingering showers and low clouds over much of the Big Island throughout the rest of the night and into early Wednesday morning.
The afternoon 00z sounding at Hilo also showed some instability over the western end of the state, which was realized in the form of a few isolated thunderstorms near the Hilo area and in the Big Island windward coastal waters this evening. Elsewhere, drier conditions are observed this evening from Kauai to Molokai, where rain gauge networks show very little rain has fallen over the past several hours. The forecast has undergone a significant update this evening to bring shower chances, QPF, and winds closer in line with the latest observations and short-term model guidance.

As the previous discussion mentioned, the state continues to reside beneath a large upper-level troughing pattern, which continues to transport moisture-rich air into the region.
Precipitable water values in excess of 2 inches continue to reside over the islands, as seen on CIMSS Precipitable Water imagery, as well as in the afternoon upper air sounding at Hilo. Despite the rich moisture in the region with scattered to numerous scattered showers possible, the middle of the week will still likely be the driest portion of the forecast, ahead of the next low pressure system forming nearby. Winds will be relatively light and variable through Wednesday night.

By the latter part of this week, the upper-level winds will become stronger and a trough will deepen into a low just west of the state. Once again, a rich plume of deep tropical moisture will be drawn over the islands, especially the eastern half of the state over Maui County and the Big Island, and will mark the return of south to southwesterly surface flow (kona winds). As a result, shower chances will increase significantly again beginning for some areas on Thursday and lasting into the weekend, including the potential for heavy rain and flooding. The latest model guidance continues to support an additional several inches of rainfall possible over portions of the state during this period.
While this next system is not anticipated to be as intense as the recent kona storm event, it is important to note that it will impact an already highly saturated environment.

Given the antecedent conditions, including elevated streams and saturated soils, even moderate rainfall rates may quickly lead to runoff issues. The threat for flash flooding will become elevated statewide by Friday, with the potential for more significant impacts persisting through the weekend. We will continue to refine the forecast over the next couple of days as details become more clear.

AVIATION
Issued at 840 PM HST Tue Mar 17 2026

A low level trough passing through Maui and the Big Island this evening will continue to drift eastward away from Maui over the next few hours. Weather conditions will improve over Maui as this trough brings more rain and low ceilings into the Big Island tonight. Expect continued MVFR conditions over Kona and Hilo airports through the morning hours. Lanai Airport may also see MVFR to IFR conditions as these saturated conditions can produce areas of fog over the island through the early morning hours.

AIRMET Sierra remains in effect for mountain obscuration over Molokai, Lanai, Maui, and the Big Island at or above 015. No other AIRMETS are currently in effect.

Light icing lingers in clouds with the freezing level around 140.

MARINE
Issued at 840 PM HST Tue Mar 17 2026

Light and variable winds prevail through midweek, with daytime sea breezes and overnight land breezes near the coasts. A ridge building to the north of the state will gradually veer to the south by Thursday into the weekend. By this weekend, a weak low approaching from the west traverses across the state and begins to lift north on Saturday, which appears likely to maintain light to moderate southerly winds for the area.

A High Surf Advisory is in effect for north facing shores of Kauai, Oahu, Molokai and Maui through tonight as the north- northwest swell peaks tonight. Surf will gradually decline into Friday as the swell shifts out of the north and north-northeast through Friday. A new small to moderate long period west- northwest swell is expected to arrive Saturday and hold through early next week.

Surf along south shores has trended up today as a fresh long period south swell is expected to peak Wednesday then gradually ease into the weekend. Surf along east facing shores will remain well below average due to the lack of trades locally and upstream.
The exception will be for east facing shores exposed to north- northeast swells expected later this week.

HFO WATCHES/WARNINGS/ADVISORIES
High Surf Advisory until 6 AM HST Wednesday for north facing shores of Niihau, Kauai, Oahu, Molokai, and Maui.