textproduct: Honolulu

SYNOPSIS

A high pressure system will linger north to northeast of the Hawaiian Islands through the middle of next week, producing moderate to breezy trades with minor fluctuations in speed. Brief increases in showers, most noticeable tonight and Sunday night, will give way to drier trades for most of next week. There is still significant uncertainty in next weekend's weather.

SHORT TERM UPDATE

Two radars are currently out of service, limiting radar coverage from Oahu to northern portions of the Big Island. Satellite imagery shows a band of low level clouds with embedded showers moving east to west across the state. Over the past 6 hours, rainfall totals ranged from 0.02 to 0.25 inches across windward areas, with less than 0.10 inches in some leeward sections. The kona slopes of the Big Island did receive slightly over 1.00 inch.

Afternoon soundings show inversion heights sloping from 5,000 ft near Lihue to 8,000 ft near Hilo. These elevated inversion heights will allow windward showers to spill over to leeward areas of the smaller islands overnight.

Inversion heights will drop to near 4,000 ft for the western half of the state and near 7,500 for the eastern half of the state as drier air filters in during the day Sunday. This will lower rainfall chances, focusing precipitation mainly along windward slopes.

Another band of low level clouds with embedded showers will increase chances of rain Sunday night into Monday. Combined with elevated inversion heights, brief showers will again spill over to leeward areas of the smaller islands.

The remainder of the short term forecast generally repeats this pattern of passing light showers focusing along windward and mauka areas during the day and slightly enhanced showers overnight with spillage to leeward areas driven by showers embedded in the trade wind flow and lingering instability aloft.

Moderate to locally breezy trades will hold through for the next few days.

PREV DISCUSSION

Issued at 346 PM HST Sat Oct 17 2026 Radar and satellite show isolated showers across the windward areas of most islands, along with the usual trade wind pattern of mostly cloudy skies windward and partly cloudy to mostly sunny leeward. Winds were mainly out of the east or northeast, averaging 10 to 20 mph, with gusts to near 30 mph in a few places.

An evolving but basically persistent surface high pressure system to out north (sometimes northeast) will be with us for the next week. This should keep the trades blowing at moderate to breezy levels. There remains some uncertainty concerning the possible development of a surface low near the islands Friday, but ensembles are not giving a clear indication of what, if anything, might form.

In the meantime, two brief periods of enhanced showers appear to be on the way - one tonight and another Sunday night. There are no indications that heavy rain or flooding is likely. After that, we are in for a period of relatively dry trades as we await anything that might develop late in the week. Winds should remain strong enough to keep any showers moving fast enough to occasionally bleed over to leeward areas, but any rainfall amounts there will be light.

AVIATION

Breezy trades will persist through the forecast period. Isolated to scattered showers will mainly be confined to windward and mauka locations. Some of the shower may produce brief periods of MVFR ceilings and visibility.

AIRMET Sierra may be needed later tonight to account for mountain obscuration along selected windward areas due to low clouds and showers.

AIRMET Tango remains in effect for for tempo moderate turbulence downwind of terrain below 9000 ft.

MARINE

Issued at 346 PM HST Sat Oct 17 2026 High pressure north of the islands maintains fresh to strong trades well into next week. The Small Craft Advisory (SCA) has been expanded in coverage to include Oahu and Kauai waters as trades are forecast to strengthen modestly tonight and tomorrow.

A mix of short period NNW swell which peaked at the outer buoys early this morning, and declining mid- long period swell (12 to 16 seconds) will keep small surf in place through tomorrow. Both of these swells drop off by Monday, allowing surf to drop to tiny levels through much of the week before a small northwest arrives towards the end of the week.

A mid to long period south-southwest swell (15 seconds) will keep above average surf in place tonight over south shores, then decline tomorrow and remain small through much of the week with background south swells. A small long period swell is possible next weekend.

Rough trade wind swell will produce above average surf for E shores through Tuesday before declining with weakening trades mid- week. Expect some wrap of NNW swell for exposed shorelines through tonight.

FIRE WEATHER

Issued at 346 PM HST Sat Oct 17 2026 Fire weather conditions will remain below critical fire thresholds into the first half of next week. Breezy winds and minimum humidity levels will not align to reach critical levels in any of our fire weather zones. The subsidence inversion heights near Maui and the Big Island will range from 6,500 to 8,000 feet through Sunday.

HFO WATCHES/WARNINGS/ADVISORIES

Small Craft Advisory until 6 AM HST Monday for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters- Kaiwi Channel-Kauai Channel-Kauai Leeward Waters-Kauai Northwest Waters-Kauai Windward Waters-Maalaea Bay-Maui County Leeward Waters-Maui County Windward Waters-Oahu Leeward Waters-Oahu Windward Waters-Pailolo Channel.