Swell Matrix

Area Forecast Discussion

National Weather Service Honolulu Hi

405 pm hst Wed apr 15 2026

Synopsis

A low pressure system lingers far north of the Hawaiian Islands, supporting light and variable winds with chances for light, brief showers into Thursday. A passing high pressure system will bring a short return to easterly trade winds with subtle drying trends from Thursday night into Saturday. Low pressure passing just north of the state will produce light southeasterly winds from Sunday into the middle of next week, with a possible increase in shower chances for at least portions of the state.

Discussion

Issued at 400 PM HST Wed Apr 15 2026

This afternoon, mid- and high clouds associated with the subtropical jet aloft continue to stream across the islands. At the surface, weak southeasterly flow is prevailing, which has allowed for afternoon sea breeze-induced buildups of low clouds along select leeward and interior locations as well. With that said, rainfall has been quite light and sparse today, with 12 hour totals as of press time showing largely a couple hundredths of an inch at most.

Light winds will linger into Thursday, maintained as low pressure north of the islands and the trailing front north of the islands moves northeast farther from the islands. Expect daytime sea breezes and overnight land breezes through Thursday, with building clouds and brief showers over island interiors during the afternoon hours, followed by clearing each night.

High pressure passing far north of the islands from Thursday night into Saturday will allow moderate easterly trade winds to briefly return to the region. These moderate trades will likely be strong enough to limit sea breeze development to terrain sheltered areas of the islands. Increasing stability and subsidence will also coincide with this period, initiating a slight drying trend.

Global models continue to suggest that a low pressure system will develop north of the state by Sunday, though there remain some differences in timing and location. Winds will also veer back southerly across the islands, drawing moisture northward in the vicinity. As the previous discussions have mentioned, as of now the low appears to track far enough north to limit heavy rain potential over the islands, though increasing instability and shower chances are possible during the second half of the weekend and into the first of next week. While moisture availability appears to be a limiting factor at this time, upper troughing (and an eventual upper low) developing over the state, and at least some modest vertical motion during the first half of next week, warrant keeping an eye on the forecast for now.

Aviation

Issued at 400 PM HST Wed Apr 15 2026

Mostly VFR through Thursday. Bands of mid-level precipitation continue moving northeast across the area this afternoon, but are not expected to create MVFR conditions. Generally light southeast winds today will become more easterly overnight and Thursday as trades return.

No AIRMETs in effect, and none are expected.

Marine

Issued at 400 PM HST Wed Apr 15 2026

Troughing to the west maintains gentle to locally moderate ESE winds through Thursday. The strongest breezes will occur through the typical windy channels surrounding Maui and the Big Island. Building high pressure then supports moderate to locally fresh trades across the waters into the weekend. A small, short- period, NW swell diminishes into Thursday and remains subdued through the weekend. A small, medium- period, S swell will boost surf along S shores through Friday then lower over the weekend. Surf along E shores remains below the seasonal average as trades remain light. However, increasing trades by week's end should brings a slight bump to surf. Low pressure advancing S along the W coast of the US next week sends a small, medium period NE swell toward the islands by midweek.

Watches, Warnings, Advisories

None.

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