textproduct: Honolulu

SYNOPSIS

Light to moderate trade winds will produce modest showers over most windward areas into early Saturday, while lingering moisture produces wetter conditions on windward Big Island. A disturbance aloft may trigger isolated heavy showers over the state late Saturday. The tail end of a front will move down the island chain late Sunday through Monday, bringing breezy northeasterly trades and drier air in its wake. Then breezy easterly trades will bring periods of windward and mauka showers through the rest of the week.

SHORT TERM UPDATE

Stubborn shallow moisture continues to produce enhanced cloud cover over the island chain with somewhat wet conditions lingering on windward Big Island. The surface trough that affected the state during the past few days is now just southeast of Big Island and drifting away, but deeper moisture pooled around this feature remains hung up on windward Big Island, where showers will gradually diminish in intensity and coverage overnight. Across the remainder of the island chain, light to moderate trades will produce mainly scattered showers along windward slopes. Lingering moisture from the above mentioned trough is manifested as increased cloud cover, with deeper moisture lingering to the southwest and west of Kauai waters.

There is an unusually high degree of disagreement between the latest runs of the GFS and ECMWF for Saturday. The GFS is maintaining a drier, light to moderate trade wind flow, even as an upper level trough approaches from the northwest. Meanwhile, the ECMWF has the upper level trough tapping the lingering moisture just southwest and west of Kauai and producing higher chances of afternoon and evening showers on Kauai and Oahu. We will be taking a closer look at the guidance overnight to determine if adjustments need to be made in the forecast.

PREV DISCUSSION

Issued at 351 PM HST Fri Oct 30 2026 Radar and satellite imagery show moderate trade winds focusing low clouds and showers over windward and mauka areas across the state this afternoon as trades finally fill in across the Big Island. With abundant tropical moisture lingering over the region, isolated heavy downpours will remain possible over the Big Island through this evening, where the greatest moisture and instability persist. Heading into Saturday, model soundings show more stable conditions developing, leading to a more typical trade wind pattern through the weekend with shallow passing windward and mauka showers.

The next pattern change arrives late Sunday into Monday as an upper-level trough sweeps across the north-central Pacific and the tail end of a frontal boundary attempts to push down the island chain. An increase in windward and mauka showers can be expected ahead of and along this boundary, with breezy northeast winds and drier air filtering in its wake as high pressure builds to the north. This will bring welcome relief from this week's muggy conditions, with dew points projected to drop into the lower 60s on Monday and Tuesday.

The surface high north of the state will become elongated as a broad low pressure system tracks across the North Pacific, maintaining breezy easterly trades across the islands through the workweek. As batches of moisture filter through on the trades, periods of enhanced windward and mauka showers can be expected. One of these upticks in shower activity looks to occur midweek as increased moisture moves in on the trade wind flow and a weak mid-level shortwave trough adds some instability as it sweeps across from the east.

By next weekend, noticeable model spread emerges between the GFS and ECMWF. While trade winds look to persist, questions remain regarding their strength and how much moisture theyll bring to the area. The GFS continues to hint at a tropical cyclone developing far southeast of the state, whereas the ECMWF does not. The National Hurricane Center continues to monitor this area, maintaining a medium (40 percent) chance of development over the next 7 days.

AVIATION

A trough to the west and ridge to the east will maintain easterly trade winds tonight through early tomorrow morning, with significant differences in model solutions beginning tomorrow mid morning. Light showers and clouds will focus over primarily windward and mountain areas tonight and tomorrow morning, although conditions are expected to gradually improve tonight. The exception will be windward Big Island, where increased moisture will linger through the forecast period, keeping lower ceilings and reduced visibility in place. Tomorrow and tomorrow evening's conditions will depend on the progression of the trough to the west. Half of our model solutions depict this feature bringing deeper moisture over Kauai and moving down to Oahu through late Saturday night, along with veering winds to the southeast. This solution would mean more showers and low ceilings/reduced visibility over Oahu and Kauai Saturday evening. The other half of our models show drier conditions with light easterly winds. There is also the chance for some pop up afternoon showers tomorrow as low level moisture associated with the trough lingers.

AIRMET Sierra for mountain obscuration remains in effect abv 020 for windward areas of the Big Island and could linger through the evening as moisture remains anchored.

MARINE

High pressure to the north will bring moderate to fresh trades to the region into the weekend. As the trades build, a Small Craft Advisory will likely be needed for the typical windier waters, and an incoming north-northwest swell will bring seas in excess of 10 feet to exposed waters.

The current small, short period north-northeast swell will maintain small surf along north-facing shores into Saturday. A larger, long-period northwest swell is expected to arrive late Saturday and will bring advisory level surf to north and west facing shores exposed to the swell Sunday into Monday. The swell is expected to shift slightly more northerly and may briefly build further on Monday before dropping Tuesday. Depending on the exact direction, a Marine Weather Statement may eventually need to be issued due to the potential for harbor surges at Kahului and Hilo during that time.

The current small, medium period south swell will gradually decline through the weekend. During the first half of next week, south shore surf will return to below seasonal averages. East- facing shores will continue to be boosted due to the wrap from the north and southerly swells. As the larger north swell builds in Sunday night and Monday, the wrap from that will have the potential for advisory level surf during that time.

FIRE WEATHER

Issued at 351 PM HST Fri Oct 30 2026 Recent rain and light to moderate trade winds will maintain low fire weather concerns through Saturday. As a weak front passes through early next week and brings breezy northeasterly winds and drier air to the region, fire weather concerns will become moderate.

HFO WATCHES/WARNINGS/ADVISORIES

None.