Marine Weather and Tide Forecast for Koloa, HI

SHORT TERM UPDATE
Forecast looks on track compared to observations and guidance. No updates expected for today.

PREV DISCUSSION
Issued at 306 AM HST Thu Jun 25 2026

An upper level low centered several hundred miles north of Hawaii is producing bands of cirrus cloud cover over the islands of Kauai and Oahu and working to enhance trade wind shower activity in the vicinity this morning. Surface high pressure centered far north of the state is also driving breezy easterly trade winds which will carry pockets of moisture and low clouds through the weekend.
Nighttime and early morning hours along windward slopes will be the prime time and location for the majority of the showers.
Isolated leeward showers will also be possible across the smaller islands, and along the Kona slopes during the afternoons. The surface high will remain nearly stationary into next week while the upper low drifts slowly to linger over the Northwestern Hawaiian Islands this weekend into the coming week.

Long range guidance suggests another influx of moisture arriving next week with dew points forecast to rise above 70 on Monday. At least the first half of the week looks to be humid, with increased chances for precipitation and heavier rain showers, especially by mid-week as a low-level trough tracks east to west across the region. There are some differences in model solutions regarding trade wind speeds due to the forecasted strength and position of the high pressure to the north, especially by mid- week.

AVIATION
Issued at 306 AM HST Thu Jun 25 2026

Moderate to breezy trades are expected through the forecast period. Low clouds and showers will favor windward and mauka areas. Expect MVFR conditions within showers and VFR elsewhere.

AIRMET Sierra is in effect for mountain obscurations for windward sections of the Big Island. Conditions may linger into the morning due to the ongoing and upstream showers. The mountain obscurations for the kona slopes have been cancelled due to conditions improving overnight.

AIRMET Tango is in effect for moderate turbulence downwind of terrain due to the breezy trade winds and will continue overnight.

MARINE
Issued at 306 AM HST Thu Jun 25 2026

High pressure to the north will dominate through at least the first half of next week, keeping moderate to locally strong trade winds in place across Hawaiian waters. A Small Craft Advisory (SCA) remains in effect for the typically windier waters around Maui and the Big Island. Although the SCA goes through Friday afternoon, it will likely be extended through the weekend.

A long period south swell will peak today with head high to overhead surf heights at most exposed south shore surf breaks, then slowly decrease Friday and Saturday. Another pulse of south swell energy will then arrive on Saturday and peak by Sunday before gradually declining next week.

Surf along east facing shores will remain rough and choppy into the weekend as breezy trades persist. Surf heights along north facing shores will remain small to tiny through the first half of next week.

HFO WATCHES/WARNINGS/ADVISORIES
Small Craft Advisory until 6 PM HST Friday for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters- Maalaea Bay-Pailolo Channel.