textproduct: Honolulu

SYNOPSIS

After a dry day Monday, we will see an increase in both moisture and trade winds Tuesday into Wednesday. This will bring an increase in showers, mainly windward and mauka. Trades will continue at moderate to occasionally breezy levels into the weekend, with the potential for a drier period Friday and Saturday.

SHORT TERM UPDATE

A few minor adjustments were made to PoPs to account for current trends. Previous forecast is on track.

PREV DISCUSSION

Issued at 336 PM HST Mon Jun 22 2026

Scattered showers were moving over Kauai County this afternoon, with only light isolated showers elsewhere. Skies were mostly sunny over the majority of the state, with the exceptions mainly over Kauai County and lower elevations of the Big Island. Winds were representative of a light to moderate trade flow, with sustained speeds averaging 10 to 15 mph, with a few gusts around 25 mph and the typical windy spots.

Relatively light trades and dry conditions will give way to increasing winds and moisture tonight into Tuesday as a surface trough approaches from the east. This will bring an increase in showers, mainly windward and mauka. PW values will increase Tuesday into Tuesday night (with the latest guidance coming in a little lower than previous runs).

Aloft, a weak upper level low to our northeast will drift southwest and come near the state Wednesday into Wednesday night before moving off to the northwest and then weakening through Sunday. This upper low will bring cooler air aloft, enhancing instability slightly for the coming week. This will lead to a deeper surface boundary and higher inversion, leading to stronger rain rates compared to the past few days. However, no widespread heavy rain is forecast. The impact will be mainly windward and mauka due to the strengthening trade winds.

North of our weak upper level low, an upper level ridge will help keep a strong surface high positioned to our northeast, off the coast of the mainland. This will keep the trades blowing a moderate to occasionally breezy levels into the weekend. Models indicate some drier air approaching Friday and Saturday, reducing the number and strength of showers.

AVIATION

Moderate to locally breezy trade winds expected through midweek. A trough east of the state moving westward will increase SHRA across most sites through Wednesday. MVFR conds can be expected as the trough passes through.

No AIRMET's are currently in effect, however AIRMET Sierra for mtn obsc might be needed overnight through tomorrow as the trough moves through.

MARINE

Issued at 336 PM HST Mon Jun 22 2026

A weak high pressure ridge will remain nearly stationary north of the waters maintaining gentle to locally fresh trade winds through Tuesday. High pressure to the far north-northeast will strengthen by mid-week, causing easterly trade winds to gradually strengthen to moderate to locally strong levels. A Small Craft Advisory (SCA) may need to be issued for the windier waters and channels around Maui County and the Big Island as early as Tuesday night with the east to west passage of a low-level trough over the islands contributing to enhanced winds behind the feature. The trough will also be accompanied by an increase in shower activity Tuesday and Wednesday. SCA conditions are then likely to continue through the end of the week.

A series of small to moderate, medium to long period south swells will keep surf along south-facing shores near seasonal average through the forecast period. A moderate, long-period swell (nearly 3 feet, 15 seconds on Buoy 2) is giving a slight boost to south shore surf this afternoon which is expected to continue through tonight before fading on Tuesday. Another boost in south swell is expected Wednesday night into Thursday below High Surf Advisory levels.

Surf along east-facing shores will remain small due to the lack of trade wind energy upstream of the islands through tonight. Easterly wind wave looks to increase Tuesday into the end of the week, reaching moderate levels as trade winds increase. Surf along north-facing shores will remain flat to tiny through the forecast period with a potential bump of tiny background energy midweek into Thursday.

HFO WATCHES/WARNINGS/ADVISORIES

None.