Marine Weather and Tide Forecast for Kahaluu-Keauhou, HI

DISCUSSION
The trade winds have eased to become light to moderate in response to the weakening pressure gradient as the surface high gets pushed farther northeast of the state and a low pressure system sets up to the north. As this low continues to drift southeastward, high pressure will build behind and will allow the northeasterly trades to gradually strengthen through the weekend.
Moderate trades are expected later this afternoon and could become locally breezy in a few areas this weekend as the remnants of a dissipating frontal boundary moves into Kauai on Saturday and over Oahu on Sunday. An increase of trade wind showers should be expected as the old frontal boundary moves through this weekend.

Also a weak trough southeast of the Big Island could bring an uptick of moisture over windward Big Island this weekend. Brief downpours will be possible, especially over the windward slopes during the afternoons.

Starting next week, a very unusual weather pattern is expected to develop over the state. A surface low is expected to develop near 15N and the international dateline this weekend. This low pressure system will gradually track eastward next week. While tracking eastward, a deep upper level trough will develop just west of the state and will transport a broad area of deep tropical moisture (with precipitable water values of up to 2.5 inches) over the state around Tuesday and Wednesday of next week. While there are still some timing differences, there is potential for significant heavy rain and flash flooding towards the middle of next week. Due to the broad band of deep moisture, it is going to be difficult to pinpoint what areas will be impacted the most and will highly depend on where the clusters of thunderstorms develop. While, heavy rain and flash flooding will be the main concern, some damaging winds will be possible with any thunderstorms.



AVIATION

Gentle to moderate trade wind weather is expected today with mostly VFR conditions. An increase of showers around PHTO could produce brief MVFR conditions later this afternoon.

A strong jet developing today with the jet streak located just north of the state could produce light to moderate turbulence around Kauai and Oahu between FL240 to FL320. Severe turbulence will be possible further north of the state especially this afternoon into Saturday morning. See SIGMET ROMEO for more information.

No AIRMET's are in effect, but we may need AIRMET TANGO later today if we begin to see reports of moderate turbulence.

MARINE
Easterly trade winds will be at gentle to moderate strength through Friday as surface low pressure far north of Hawaii and a nearby surface trough weaken the local pressure gradient. Trades are expected to hold at current strength and shift out of the northeast this weekend as high pressure far northwest of Hawaii pushes the low eastward. The weaker trade winds should persist Monday, but uncertainty increases on Tuesday, hinging on the potential development of a low southwest of the islands.

A small, medium-period northwest swell will arrive overnight and provide a small boost to surf along north-facing shores on Friday.
A moderate, medium-period north-northwest swell will build late Saturday and peak around seasonal average on Sunday. As this swell declines on Monday, a long-period west-northwest swell will arrive, maintaining small to moderate surf into the middle of next week.

Small background level surf will prevail along south-facing shores through Friday. A small to moderate south-southwest swell is expected to boost surf to around seasonal average this weekend into early next week.

Along east-facing shores, trade-wind swell will continue to decrease through Friday, though a small, medium-period northeast swell may maintain small surf through Saturday. Aside from wrapping north-northwest swell in exposed areas, east shore surf should remain below seasonal average much of next week.



FIRE WEATHER
Issued at 329 AM HST Fri Oct 23 2026

Moderate trade winds with mostly dry conditions over leeward areas will continue to produce low to moderate fire weather conditions through the weekend. Ample tropical moisture will move in from the southwest sometime beginning Monday night or Tuesday, bringing a threat for heavy rain through the middle of the week.
As a result, fire weather concerns will be low next week. Inversion heights will range from 6,000 to 8,000 feet today and will be relatively weak over the eastern end of the state due to a weak trough southeast of the Big Island.



HFO WATCHES/WARNINGS/ADVISORIES
None.