textproduct: Honolulu

SYNOPSIS

Moderate to locally breezy trades will continue to bring isolated to scattered showers to windward and mauka areas through this evening. Winds will begin to ease tonight, then turn out of the south by midweek as an area of low pressure develops to the north of the state. Rain chances and the potential for heavy rain will increase during the second half of the week.

SHORT TERM UPDATE

Current radar and satellite imagery show isolated to scattered showers moving into windward and mauka areas of the state on the moderate to locally breezy trades this morning, with a higher concentration focused over windward portions of Maui and the Big Island. Over the next couple of hours, not much will change besides a slight reduction in shower coverage for windward Maui and Big Island as drier air filters in, and the addition of showers developing over the kona slopes of the Big Island this afternoon. Winds are still on track to weaken overnight into Tuesday, allowing for a hybrid lighter tradewind and land/sea breeze pattern to develop with showers favoring windward and mauka areas overnight, then daytime heating will induce clouds and a few showers over leeward areas tomorrow afternoon.

DISCUSSION

Issued at 339 AM HST Mon Oct 5 2026

Latest surface analysis shows high pressure north of the state and a weak disturbance passing to the south, resulting in breezy trade winds. Radar and satellite imagery show scattered low clouds with embedded light showers. Overnight rainfall totals range from .20 to .30 inches of rainfall mostly for windward and mauka areas of Maui County and the Big Island. Modest amounts were observed over the the rest of the state as shower coverage becomes more isolated. Chances of showers will trend down through the day today. Winds will gradually ease later today and tonight as the high north of the state weakens and shifts northeast. Showers will remain limited along windward and mauka areas.

A hybrid land/seabreeze and light trade wind pattern will develop Tuesday as winds continue to ease. Winds will then veer southeasterly by late Tuesday, and south by Wednesday, as a sharp trough approaches from the northwest. A surface low will form along the trough and southerly winds will draw deep tropical moisture over the islands, while a cold pool aloft associated with the upper low will act to destabilize the atmosphere over the state. PW values will increase to around 2 inches and dewpoints will rise to around 70 Thursday and into the lower 70s Friday. As this deeper moisture moves in with increasing instability, heavy rain will become likely. The timing and location of the moisture continues to be depicted slightly different in the long range models, but at this time it appears all the islands will be impacted at some point. Thus, not getting too specific in the forecast details for now, but expect an overall wetter pattern and southerly winds from around late Wednesday through at least Friday, and possibly lingering into the upcoming weekend.

AVIATION

Moderate to breezy trade winds will continue across the region today with isolated showers favoring windward and mountain areas where short-lived MVFR conditions are possible. Otherwise, VFR conditions will prevail across the state.

AIRMET Sierra remains in effect for mountain obscuration across windward and mountain areas of Maui and the Big Island. Conditions over these areas may temporarily improve as the day progresses, but showers upstream will likely keep this AIRMET in effect for some windward and mountain areas through today.

AIRMET Tango also remains in effect for moderate turbulence downwind of mountain terrain due to the breezy trades.

MARINE

Issued at 339 AM HST Mon Oct 5 2026

High pressure north of the Hawaiian Islands will maintain fresh to locally strong trade winds today. The Small Craft Advisory for the windier waters and channels around Maui County and the Big Island remains in effect through this afternoon. Thereafter, high pressure to the north weakens and trades will start to diminish. Troughing developing northwest of the islands will likely cause winds to veer out of the southeast around midweek and bring increased shower activity for the latter half of the week.

A new small, long-period south swell will slowly fill in today and tonight, causing surf along south and west facing shores to increase to slightly above seasonal averages Tuesday into Wednesday. Surf is then forecast to drop to near or slightly below average for the rest of the week, maintained by a mix of new, small south swells.

A small, medium-period northwest swell builds this morning and peaks late today, producing a small bump in surf along north-facing shores that begins fading on Tuesday. However, a larger, long-period northwest swell will arrive on Tuesday that will push surf higher into Wednesday. Surf is then likely to hold through the end of the week even as swell energy becomes shorter period as it is reinforced by a low to the north-northwest of the Hawaiian Islands. Surf along east facing shores will fall below seasonal averages as locally strong trades diminish tonight.

A small, long-period west swell originating from Typhoon Choi-wan is forecast to reach the islands Thursday into the weekend, which may produce moderate surf for west-facing shores of the Big Island.

FIRE WEATHER

Issued at 339 AM HST Mon Oct 5 2026

Breezy trades will gradually ease later today into Tuesday with RH values just above the critical threshold for fire weather each afternoon through Tuesday. Fire weather risk then diminishes through the remainder of the week as moisture increases, winds decrease, and showers increase in coverage. The inversion should range from 7 kft to 8 kft through Tuesday.

HFO WATCHES/WARNINGS/ADVISORIES

Small Craft Advisory until 6 PM HST this evening for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters- Maalaea Bay-Pailolo Channel.