textproduct: Honolulu

SYNOPSIS

Trades will quickly dissipate tonight as an upper level trough swings through the state tonight into Saturday. Expect increasing chances for heavy rain and isolated thunderstorms through Saturday especially along windward areas. The threat for heavy rain and thunderstorms should diminish by Saturday evening as the main trough axis lifts north of the state. Strengthening trades around Tuesday of next week will bring some showery weather, followed by more stable conditions by mid to late week.

DISCUSSION

Issued at 404 PM HST Fri Feb 20 2026

Water vapor imagery is showing a short-wave trough approaching the state this afternoon from the west, which should help produce showers and isolated thunderstorms over the western half of the state tonight. A Flood Watch remains in effect for Kauai and Niihau through tonight, and the latest HREF model agrees with the heaviest rainfall rates occurring during the evening and overnight hours. Unstable and showery conditions should persist on Saturday, but the greatest flooding risk should be tonight as the upper trough swings through Kauai.

Over on Oahu, we are seeing showers training along the Ko'olau Range this afternoon. Low level winds have weakened and veered toward the east-southeast and we are seeing a plume of moisture drifting towards Oahu from Molokai. Training showers will likely continue along the Ko'olau range through this evening, which will lead to rises along the streams and some minor flooding possible along low lying areas. For the most part, rainfall rates have been holding in the 0.5 to 1 inch per hour rate, but rainfall rates could increase this evening as instability increases from the approaching upper level trough. The upper level trough should bring an increase of showers and isolated thunderstorms late tonight into Saturday for Oahu. For rest of the state, showers should be on the increase Saturday, with windward areas likely seeing the greatest shower coverage. Isolated thunderstorms will be possible, but if any thunderstorms do form, they will likely be brief and isolated. Some localized flooding impacts will be possible, especially windward areas. The summits of the Big Island could also see some snow showers Saturday afternoon, which may prompt a Winter Weather Advisory.

By Sunday, the main moisture axis should lift off to our north and while conditions aloft will still be unstable, we will lack the moisture on Sunday. So overall Sunday should start off fairly nice, with sea breezes developing during the day. Sea breezes should allow for some afternoon clouds and showers over interior and mountain areas. Any showers that do develop could be heavier than usual due to the instability aloft.

Beyond the weekend, model guidance suggests the main band of moisture staying north of the state through Monday. As high pressure builds north of the state Monday night into Tuesday, this band of moisture will ride in with the returning trade winds Tuesday into Tuesday night. By the second half of next week, mid- level ridging is expected to build overhead, supporting a more stable pattern with moderate to breezy trade winds.

AVIATION

Issued at 404 PM HST Fri Feb 20 2026

Trade winds will weaken this evening and Saturday as the pressure gradient weakens and an upper level trough moves over the islands from the west. Showers are expected to increase in coverage from west to east tonight through Saturday. We expect localized MVFR and isolated IFR in the strongest showers.

AIRMET Sierra is in effect for mountain obscuration above 2 kft for north through southeast Oahu, east Maui, and north and east Big Island due to showers.

AIRMET Tango remains in effect for tempo moderate turbulence below 8000 feet over leeward sides of the islands as a result of continued breezy low level winds. Conditions are expected to improve as winds weaken tonight.

MARINE

Issued at 404 PM HST Fri Feb 20 2026

Strong trades will persist today, then begin to ease over the weekend as a gale nearby to the NW lifts NNE and away from the region. Winds may become light enough for a localized land and sea breeze regime to become established over the weekend. Seas will respond by gradually lowering, likely falling below the 10 ft Small Craft Advisory level by early Saturday. In addition to the winds and seas, expect a wet pattern with isolated thunderstorms to develop by tonight as an upper disturbance moves over the state.

Nearshore PacIOOS buoys indicate NE energy through the entire spectrum, encompassing wind wave action and fresh trade wind swell propagating through area waters. Swell still hovers near the advisory threshold at forecast issuance time this afternoon as it lags the decrease in winds by at least several hours. The High Surf Advisory has therefore been extended through tonight. A downward trend is then expected over the weekend as winds diminish both locally and upstream.

Impactful NNE swell anticipated early next week. Surf along exposed N and E shores will quickly build through the day Monday as a long-period NNE (020) swell from a broad storm-force low evolves off the Pacific NW coast coast this weekend. A large area of northerly gales between this system and a 1048 mb blocking high centered over the Aleutians will expand southward Friday through the weekend, with the head of the fetch reaching less than 1,000 nautical miles from the state. Surf will reach High Surf Warning thresholds for exposed N and E shores by late Monday through Tuesday. Although a gradual downward trend is anticipated by midweek, additional pulses from this same system will keep surf above the advisory threshold for E shores through much of next week. This swell direction will bring surf into some typically protected areas such as Kua Bay, West Maui, and exposed shores of Lanai.

Next week's NNE (020) swell will also produce significant erosion along some coasts and accretion at other locations as sand shifts opposite the typical swell direction, particularly along N facing shores. Overwash of roads and vulnerable sections of coastline is likely beginning Monday night during high tide cycles. Mariners can also anticipate harbor surges in Kahului and Hilo.

Surf along exposed W shores will rise early next week as a long- period NW swell arrives from a broad storm-force low currently located over the far northwest Pacific near the Kurils.

HFO WATCHES/WARNINGS/ADVISORIES

Flood Watch through late tonight for Kauai East-Kauai Mountains- Kauai North-Kauai South-Kauai Southwest-Niihau.

High Surf Advisory until 6 AM HST Saturday for Big Island East- Big Island North-Big Island Southeast-East Honolulu-Kauai East- Kauai South-Kipahulu-Koolau Windward-Maui Windward West-Molokai Southeast-Molokai Windward-Olomana-Windward Haleakala.

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