textproduct: Honolulu

SYNOPSIS

A weak surface trough and its associated moisture plume will progress northwestward up the island chain through Friday, bringing a slight uptick in shower activity as it passes through. Otherwise, a lighter background flow will allow for a sea/land breeze pattern to persist into the weekend with showers developing over leeward and interior areas each afternoon, followed by clearing at night. Then trade winds will gradually strengthen late this weekend through next week, shifting the shower focus to windward and mauka areas.

SHORT TERM UPDATE

Adjustments were made to PoP due to the trough moving over Molokai. Increased showers expected. Outside of that previous forecast is in good shape.

PREV DISCUSSION

Issued at 311 PM HST Wed Jun 17 2026

A weak surface trough passing over the eastern end of the state this afternoon will very gradually move up the island chain through Friday before lifting north of the area and dissipating. A plume of moisture accompanying this trough will help bring increased cloud and shower coverage in its vicinity as it progresses northwestward. The positioning of this surface trough and a series of fronts passing well north of the state will keep the trade winds disrupted through the rest of the work week and into the weekend, with generally moderate east-southeasterly winds across the eastern half of the state and light to moderate east- southeast winds across the western half. This weaker, slightly veered low-level wind pattern will allow a sea and land breeze cycle to commence, bringing clouds and a few showers across leeward and interior areas each afternoon, and clearing overnight. However, increased cloud cover in the vicinity of the trough may inhibit the sea and land breeze cycle.

Trade winds will gradually ramp up late this weekend through next week, becoming moderate to breezy by Wednesday as the surface trough weakens and moves westward, and the subtropical high to the far northeast finally regains control over the Central Pacific. Batches of moisture will filter in on the strengthening trades, supporting periodic upticks in windward and mauka showers next week.

AVIATION

A weak surface trough near the Big Island will continue moving northward, bringing chances of light showers to windward sections of Big Island and Maui. Winds will continue weakening through tomorrow, allowing daytime sea breezes and overnight land breezes to occur. Afternoon clouds and showers over island interiors are likely tomorrow. MVFR conditions are expected within showers, while VFR prevails elsewhere.

AIRMET Sierra remains in effect for mountain obscuration for windward Big Island and all of Maui due to this ongoing surface trough. Both islands are expected to see improving conditions overnight, however the western half of the state may need to be included in this AIRMET as this system continues to move northward.

MARINE

Trade winds will be mostly at gentle to moderate strength during the next few days as the surface ridge to the north remains weak and a broad surface trough drifts over the islands. The weak trough will produce scattered showers across Big Island and Maui County waters tonight and will slowly move to the northwest Thursday. Trades may increase slightly over the weekend, with more pronounced strengthening early next week as high pressure builds to the north.

A series of southern hemisphere swells will continue to move through the area during the next week, though much smaller than the recent large event. Nearshore PacIOOS Lanai and Barber Point buoys show the current swell nearly unchanged from this morning at 3.5 to 4 ft with the period dropping to 13 to 14 seconds. Expect this swell to decline slightly into tonight as forerunners from a new overlapping south-southwest swell arrive. NOAA buoy 51002 south of Hawaii has recently shown some increase in 17 second energy, and we will get a better handle on potential surf heights as more data comes in tonight. During the peak of the swell Thursday, south shore surf may climb to near the High Surf Advisory threshold of 10 feet. This swell will decline Friday, and a series of smaller south-southwest swells will maintain surf near seasonal average this weekend into early next week.

Small surf will prevail on north and east shores through most of the coming week. A slight increase in east shore surf is expected around next Tuesday or Wednesday as trade winds build across the region.

MARINE

Issued at 311 PM HST Wed Jun 17 2026

Trade winds will be mostly at gentle to moderate strength during the next few days as the surface ridge to the north remains weak and a broad surface trough drifts over the islands. The weak trough will produce scattered showers across Big Island and Maui County waters tonight and will slowly move to the northwest Thursday. Trades may increase slightly over the weekend, with more pronounced strengthening early next week as high pressure builds to the north.

A series of southern hemisphere swells will continue to move through the area during the next week, though much smaller than the recent large event. Nearshore PacIOOS Lanai and Barber Point buoys show the current swell nearly unchanged from this morning at 3.5 to 4 ft with the period dropping to 13 to 14 seconds. Expect this swell to decline slightly into tonight as forerunners from a new overlapping south-southwest swell arrive. NOAA buoy 51002 south of Hawaii has recently shown some increase in 17 second energy, and we will get a better handle on potential surf heights as more data comes in tonight. During the peak of the swell Thursday, south shore surf may climb to near the High Surf Advisory threshold of 10 feet. This swell will decline Friday, and a series of smaller south-southwest swells will maintain surf near seasonal average this weekend into early next week.

Small surf will prevail on north and east shores through most of the coming week. A slight increase in east shore surf is expected around next Tuesday or Wednesday as trade winds build across the region.

HFO WATCHES/WARNINGS/ADVISORIES

None.