Swell Matrix

Area Forecast Discussion

National Weather Service Honolulu Hi

845 pm hst Mon Sep 28 2026

Synopsis

Moderate to locally breezy trade winds will veer from the southeasterly direction by Tuesday with a gradual weakening trend. Clouds and showers will increase Tuesday through Thursday as Nolo passes to the west pulling up deep tropical moisture along the east side of the storm increasing showers over Niihau, Kauai and Oahu. Nolo moves away to the northwest by this weekend with drier easterly trade winds building back in across the Hawaii Region.

Aviation

Moderate to locally breezy trade winds will veer from the southeasterly direction by Tuesday with a gradual weakening trend. Isolated showers are possible across windward and mountain areas tonight into Tuesday with brief MVFR conditions. Moisture will increase across Kauai and Oahu Tuesday afternoon into Wednesday bringing an increased likelihood of showers. Showers are most likely across Kauai starting late Tuesday morning with shower chances gradually increasing for Oahu late Tuesday into Wednesday.

AIRMET Tango remains in effect for moderate turbulence below 9,000 feet over and immediately downwind of island terrain. This AIRMET will likely be needed at least through Wednesday.

Marine

Strong east trades become moderate to breezy out of the southeast tonight in response to Hurricane Nolo advancing northwestward. The exception will be around Kauai where proximity to Nolo will allow for the gradient to remain strong. Near gales will be possible immediately west of Kauai tonight through Wednesday, particularly in the channel between Kauai and Niihau. Here, the Small Craft Advisory (SCA) has been extended through Wednesday for both winds and seas. Elsewhere, the SCA remains in place and is still scheduled to expire Tuesday morning. Winds remain southeasterly through Friday as Nolo creeps slowly westward away from the islands. Once it begins to accelerate away over the weekend, east to northeasterly trades return.

Tiny long period energy out of the south is noted on the Barber's Point PacIOOS Buoy this afternoon. This energy represents the initial forerunners of a rather small (about 1 foot), long-period swell that will maintain elevated surf for south shores through mid-week. This is separate from the more substantial short to medium period fresh swell emanating from Nolo. Uncertainty related to the size of Nolo's swell coupled with its slow forward motion Tuesday night through Wednesday will be a theme in the forecast for the next couple of days. For Kauai/Niihau in particular, high surf may linger into midweek conditional on the exact size of Nolo's swell. Likewise, as Nolo lifts north, its westerly swell influence will increase, potentially supporting an HSA for Big Island-West during the middle of this week.

Surf along east shores slowly declines as trades veer southeast and diminish, then return as light to moderate easterlies this weekend. A small, long-period south swell originating east of New Zealand is poised to arrive early next week in maintenance of elevated surf along south-facing shores.

For north-facing shores, the existing small, medium-period swell fades through Wednesday. Multiple rounds of tiny swell originating out of the northwest quadrant will reach north and select west facing exposures next week as the storm track in the vicinity of the Aleutian Islands becomes increasingly active.

Watches, Warnings, Advisories

High Surf Advisory until 6 AM HST Tuesday for Kauai South-Kauai Southwest-Niihau.

Small Craft Advisory until 6 PM HST Wednesday for Kauai Leeward Waters-Kauai Northwest Waters.

Small Craft Advisory until 6 AM HST Tuesday for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters- Big Island Windward Waters-Kaiwi Channel-Kauai Channel-Kauai Windward Waters-Maui County Leeward Waters-Maui County Windward Waters-Oahu Leeward Waters-Oahu Windward Waters-Pailolo Channel.

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