textproduct: Honolulu

SYNOPSIS

Trade winds weaken Thursday as a surface trough passes over the islands. The trough also brings an increase in moisture that will produce an uptick in shower activity through Friday. A new potential tropical system is forming southeast of the state (90% chance of formation). Forecasts from the National Hurricane Center will likely begin Thursday morning.

SHORT TERM UPDATE

Forecast looks on track for tonight and Thursday, so no updates are anticipated this evening. Forecasts from the National Hurricane center regarding the potential tropical cyclone (EP90) will likely begin Thursday morning.

PREV DISCUSSION

Issued at 533 PM HST Wed Aug 19 2026 We are fully focused on the potential for tropical storm development to our ESE, and we expect the NHC to begin official forecasts late tonight or early Thursday morning. At this time, models suggest it could track similarly to Lala. However, because a clear center has yet to form, it is impossible to accurately predict (with any confidence) the details we all want to know.

While we wait for the system to form, we will go ahead and discuss what we expect over the next couple of days. Trades will weaken notably Thursday as a surface trough moves over the islands from east to west. Winds will be weaken enough to allow for a sea-breeze to develop in some leeward areas, increasing the chance of showers there. Friday, we'll see winds slowly increase in speed and veer to easterly. We'll see typical trade showers, mainly over windward and mauka areas, and most common at night, through Friday night and perhaps into Saturday. Winds and precipitation over the weekend will be highly dependent on the track of the tropical system developing to our ESE at this time.

It is likely that precipitation will increase on the east side of the state Saturday night into Sunday, and then remain high Sunday night into Monday. On the west side, precipitation will likely increase Sunday into Sunday night, and last into Monday or Monday night. Exact timing is impossible to pin down at this time. Wind speeds will depend on how close it ends up coming to each island. We urge folks to stay tuned for each new forecast as things will become clearer and better defined rapidly over time. And as we noticed with Lala, there will probably be a surprise or two even after the models seem to have come into agreement.

AVIATION

Issued at 533 PM HST Wed Aug 19 2026 Moderate trades expected through tomorrow. Some windward and mauka SHRA possible with isol MVFR conds, especially into Thursday.

A tropical Cyclone may impact the region late this weekend.

No AIRMETs are currently in effect.

MARINE

Issued at 533 PM HST Wed Aug 19 2026 High pressure to the far northeast will gradually weaken over the next couple of days. As a trough to the east of the islands passes on a westward track across the region, moderate trades will become light and variable for most waters by Thursday, allowing daytime sea breezes and overnight land breezes to become established. By late Friday, moderate to locally fresh trades will begin to build back into the region as the high drifts southward closer to the island chain and an area being watched closely for potential tropical development nears the state from the southeast. The forecast for this weekend will depend on how this next potential tropical cyclone evolves.

Surf along south facing shores will remain slightly below average through Thursday, with background swell energy in place. A long period south-southwest swell generated from gales just south and east of New Zealand will begin arriving late Thursday into Friday, boosting surf to near average. Surf along east facing shores will continue to fade as background flow becomes weaker, then build heading into this weekend as the trades restrengthen. North facing shores will remain tiny through Friday, with a slight bump from Lala swell (290 to 300 degrees) possible this weekend.

FIRE WEATHER

Issued at 533 PM HST Wed Aug 19 2026 Trade winds will weaken Thursday, increasing chances of showers for the leeward side of the islands. Trade winds increase over the weekend with showers switching to windward. The inversion is 6000 to 7000 ft. The potential for another tropical storm to bring heavy rain and wind to the state this weekend is becoming high.

HFO WATCHES/WARNINGS/ADVISORIES

None.