Marine Weather and Tide Forecast for Kahului, HI

SHORT TERM UPDATE
Radar and satellite imagery show scattered to numerous showers moving into windward and mauka areas of the Big Island through Oahu at the time of this mid morning update. Based on the upstream moisture seen on satellite, this band of moisture will work its way across the island chain through the day with scattered showers expected to continue to move into windward and mauka areas on the breezy trades. The current forecast remains on track, with no changes needed.

PREV DISCUSSION
Issued at 322 AM HST Wed Jun 10 2026 Short-range guidance remains in good agreement and depicts breezy easterly trade winds persisting today as a strong subtropical ridge remains anchored north of the state. A band of moisture over the eastern end of the state, combined with an elevated trade wind inversion near 10 kft and a weak upper-level trough, has led to showery conditions over windward sections of the Big Island and Maui this morning. Overnight upper air sounding at Hilo shows a modest increase in low-level moisture associated with this band, with precipitable water values above climatological normals to 1.57 inches. The latest rainfall summary reflects this showing peak accumulations nearing an inch in some of the windward Maui gauges over the past six hours (ending at 2 AM HST). This moisture may linger through Thursday morning, supporting enhanced rainfall chances across windward areas, potentially expanding to all windward sections of the island chain by tonight.

The surface ridge north of the islands is forecast to weaken from Thursday through Saturday, allowing trade winds to ease into the light to moderate range. At the same time, a drier and more stable air mass is expected to move into the region. As a result, shower activity should become more limited, with passing showers favoring windward and mauka areas during the overnight and early morning hours. Localized sea breezes will develop each afternoon, leading to a few clouds and showers over interior and leeward areas, particularly from Thursday through Saturday.

By late in the weekend and into early next week, strengthening surface ridge north of the state should support a return to a more typical breezy trade wind pattern.

AVIATION
High pressure north of the islands will sustain moderate to locally breezy ENE trade winds today and then decrease a little later tonight. An area of enhanced moisture over the eastern half of the state will continue to bring MVFR showers to Big Island and Maui windward areas today and could spread to the other islands later today and tonight at a lesser extent. MVFR conditions are expected within showers, while VFR prevails elsewhere.

AIRMET Sierra is in effect for windward Oahu, Maui, Molokai, and the Big Island due to frequent shower activity causing mountain obscuration. These conditions are expected to generally continue through today.

MARINE
Surface ridge north of the area will hold today maintaining moderate to locally fresh trades. The ridge will weaken Thursday through Saturday as a front passes far north of the state. Trades will ease into the light to moderate category during this time.
Fresh to locally strong easterly trades will return Sunday through early next week.

A series of southern hemisphere swells will continue through the rest of the week with a large south swell due to arrive this weekend into early next week. Currently, a small, medium-period south swell is fading. Near seasonal average surf along south facing shores will gradually decline today through Thursday. A smaller pulse of south- southwest swells will fill in late Thursday into Friday keeping surf elevated along south facing shores.

Long-period energy from a storm that passed within our swell window around New Zealand earlier this week is expected to gradually fill in locally through the weekend. Wave models have this swell peaking Sunday into Monday that will likely drive surf heights near or above warning level. This swell will coincide with the peak monthly tides and will likely lead to significant wave runup and minor coastal flooding during the first half of next week, particularly during the peak daily high tide cycles.

A small west-northwest swell will fade today into Thursday. East shore surf will slowly decline below seasonal averages through the rest of the week as trades ease.

HFO WATCHES/WARNINGS/ADVISORIES
None.