West Kaua’i

Tonight: Partly cloudy. Isolated showers in the evening. Lows around 74 near the shore to around 64 above 3000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Thursday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 86 to 92 near the shore to around 78 above 3000 feet. North winds up to 10 mph shifting to the west in the afternoon. Chance of rain 20 percent.

Thursday Night: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows around 75 near the shore to around 65 above 3000 feet. Light winds. Chance of rain 40 percent.

South Kaua’i

Tonight: Partly cloudy with isolated showers. Lows 72 to 77. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Thursday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 80 to 91. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Thursday Night: Mostly cloudy with scattered showers. Lows 72 to 77. Northeast winds around 10 mph. Chance of rain 50 percent.

Kaua’i Mountains

Tonight: Mostly cloudy with scattered showers. Lows around 70 in the valleys to around 62 above 4000 feet. East winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Thursday: Partly sunny with scattered showers. Highs 76 to 83 in the valleys to around 70 above 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Thursday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows around 70 in the valleys to around 62 above 4000 feet. Light winds. Chance of rain 70 percent.

North Kaua’i

Tonight: Partly cloudy with isolated showers. Lows 66 to 75. Southeast winds up to 15 mph. Chance of rain 20 percent.

Thursday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 72 to 88. East winds up to 15 mph shifting to the northeast in the afternoon. Chance of rain 40 percent.

Thursday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 66 to 76. East winds up to 10 mph in the evening becoming light. Chance of rain 60 percent.

East Kaua’i

Tonight: Mostly cloudy with scattered showers. Lows 68 to 77. Northeast winds up to 10 mph. Chance of rain 40 percent.

Thursday: Partly sunny with scattered showers. Highs 80 to 88. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Thursday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 68 to 77. Northeast winds up to 10 mph in the evening becoming light. Chance of rain 60 percent.

Detailed Forecast

Synopsis

Trade winds weaken Thursday as a surface trough passes over the islands. The trough also brings an increase in moisture that will produce an uptick in shower activity through Friday. A new potential tropical system is forming southeast of the state (90% chance of formation). Forecasts from the National Hurricane Center will likely begin Thursday morning.

Short term update

Forecast looks on track for tonight and Thursday, so no updates are anticipated this evening. Forecasts from the National Hurricane center regarding the potential tropical cyclone (EP90) will likely begin Thursday morning.

Prev discussion

Issued at 533 PM HST Wed Aug 19 2026 We are fully focused on the potential for tropical storm development to our ESE, and we expect the NHC to begin official forecasts late tonight or early Thursday morning. At this time, models suggest it could track similarly to Lala. However, because a clear center has yet to form, it is impossible to accurately predict (with any confidence) the details we all want to know.
While we wait for the system to form, we will go ahead and discuss what we expect over the next couple of days. Trades will weaken notably Thursday as a surface trough moves over the islands from east to west. Winds will be weaken enough to allow for a sea-breeze to develop in some leeward areas, increasing the chance of showers there. Friday, we'll see winds slowly increase in speed and veer to easterly. We'll see typical trade showers, mainly over windward and mauka areas, and most common at night, through Friday night and perhaps into Saturday. Winds and precipitation over the weekend will be highly dependent on the track of the tropical system developing to our ESE at this time.
It is likely that precipitation will increase on the east side of the state Saturday night into Sunday, and then remain high Sunday night into Monday. On the west side, precipitation will likely increase Sunday into Sunday night, and last into Monday or Monday night. Exact timing is impossible to pin down at this time. Wind speeds will depend on how close it ends up coming to each island. We urge folks to stay tuned for each new forecast as things will become clearer and better defined rapidly over time. And as we noticed with Lala, there will probably be a surprise or two even after the models seem to have come into agreement.

Aviation

Issued at 533 PM HST Wed Aug 19 2026 Moderate trades expected through tomorrow. Some windward and mauka SHRA possible with isol MVFR conds, especially into Thursday.
A tropical Cyclone may impact the region late this weekend.
No AIRMETs are currently in effect.

Marine

Issued at 533 PM HST Wed Aug 19 2026 High pressure to the far northeast will gradually weaken over the next couple of days. As a trough to the east of the islands passes on a westward track across the region, moderate trades will become light and variable for most waters by Thursday, allowing daytime sea breezes and overnight land breezes to become established. By late Friday, moderate to locally fresh trades will begin to build back into the region as the high drifts southward closer to the island chain and an area being watched closely for potential tropical development nears the state from the southeast. The forecast for this weekend will depend on how this next potential tropical cyclone evolves.
Surf along south facing shores will remain slightly below average through Thursday, with background swell energy in place. A long period south-southwest swell generated from gales just south and east of New Zealand will begin arriving late Thursday into Friday, boosting surf to near average. Surf along east facing shores will continue to fade as background flow becomes weaker, then build heading into this weekend as the trades restrengthen. North facing shores will remain tiny through Friday, with a slight bump from Lala swell (290 to 300 degrees) possible this weekend.

Fire weather

Issued at 533 PM HST Wed Aug 19 2026 Trade winds will weaken Thursday, increasing chances of showers for the leeward side of the islands. Trade winds increase over the weekend with showers switching to windward. The inversion is 6000 to 7000 ft. The potential for another tropical storm to bring heavy rain and wind to the state this weekend is becoming high.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov