West Kaua’i

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows around 76 near the shore to around 67 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Thursday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 87 to 92 near the shore to around 78 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Thursday Night: Mostly cloudy with scattered showers. Lows around 76 near the shore to around 66 above 3000 feet. Northeast winds 10 to 15 mph decreasing to up to 15 mph after midnight. Chance of rain 50 percent.

South Kaua’i

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then showers likely after midnight. Lows 72 to 78. Northeast winds 15 to 20 mph. Chance of rain 60 percent.

Thursday: Partly sunny. Breezy. Scattered showers in the morning, then showers likely in the afternoon. Highs 80 to 90. Northeast winds 15 to 20 mph. Chance of rain 60 percent.

Thursday Night: Mostly cloudy with showers likely. Lows 72 to 78. Northeast winds around 15 mph. Chance of rain 70 percent.

Kaua’i Mountains

Tonight: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows around 72 in the valleys to around 64 above 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Thursday: Mostly cloudy. Breezy. Showers likely in the morning, then occasional showers and slight chance of thunderstorms in the afternoon. Highs 74 to 82 in the valleys to around 68 above 4000 feet. Northeast winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 90 percent.

Thursday Night: Mostly cloudy. Breezy. Occasional showers in the evening, then showers likely after midnight. Lows around 71 in the valleys to around 63 above 4000 feet. Northeast winds 10 to 20 mph. Chance of rain 90 percent.

North Kaua’i

Tonight: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows 67 to 77. East winds 10 to 15 mph decreasing to up to 15 mph after midnight. Chance of rain 70 percent.

Thursday: Breezy. Mostly cloudy with showers likely. Highs 71 to 88. Northeast winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 70 percent.

Thursday Night: Mostly cloudy. Occasional showers in the evening, then showers likely after midnight. Lows 67 to 76. East winds 10 to 15 mph. Chance of rain 90 percent.

East Kaua’i

Tonight: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows 68 to 78. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Thursday: Mostly cloudy. Breezy. Showers likely in the morning, then showers likely and slight chance of thunderstorms in the afternoon. Highs 79 to 86. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

Thursday Night: Cloudy. Occasional showers and slight chance of thunderstorms in the evening, then showers likely after midnight. Lows 68 to 77. Northeast winds 10 to 15 mph. Chance of rain 90 percent.

Detailed Forecast

Synopsis

Breezy trades expected through the middle of next week. An upper level trough and moisture associated with the remnants of Norbert will fill in across the state from east to west Thursday into Friday, increasing the chances of heavy rain, isolated thunderstorms, and flash flooding, especially for the windward and mauka areas. Drier air will move back in this weekend behind the departing trough. Moisture from the remnants of Tropical Depression 15-E may bring another round of enhanced trade showers around next Tuesday and Wednesday.

Discussion

Afternoon satellite imagery shows an upper level low around 1400 mi north- northeast of the islands with a trough extending southwestward. Isolated light showers continue to move westward with the greatest coverage from Maui northward. Trade winds will continue to strengthen through the afternoon as the upper trough approaches.
The upper level trough will dig southwest tonight into Thursday, pulling in remnant moisture from Norbert. Satellite imagery shows a broad area of precipitable water in excess of 2″ beginning to move into the Big Island, and is forecast to move across the remaining islands tonight into Thursday. Deeper moisture and increasing instability will bring moderate to locally heavy showers and a slight chance of thunderstorms, with the highest threat of thunderstorms across the Big Island Thursday afternoon. Heaviest rain is expected on the windward and mauka areas. With soil moisture likely still high from previous heavy rain events, there is an increased risk of flash flooding where heavier showers and thunderstorms occur.
Moisture will decrease from east to west late Friday through the weekend. There is the potential for another round of increasing moisture from the remnants of tropical depression 15-E moving into around Tuesday to Wednesday of next week. Ensembles show at least a weak low-level wave associated with this moisture, though further aloft only 6% of the ensemble members have some form of troughing while the remainder keep us under a ridge, limiting the potential for heavier showers.

Aviation

Moderate to locally breezy trade winds will strengthen to breezy levels this afternoon and a trough will approach the area from the east. Showers and low clouds associated with that trough will increase with the trade wind flow from east to west starting early tonight for the eastern half of the state, then spread west late tonight into tomorrow morning. More widespread MVFR conditions will be possible as the moisture associated with the trough moves in, especially for windward and mountain areas.
No AIRMETs are currently in effect. There is the possibility for AIRMET Tango during the afternoon once trade winds strengthen. There is also potential for AIRMET SIERRA later today as clouds increase on the windward slopes.

Marine

A broad trough, associated with the remnants of Tropical Storm Norbert, will approach the state from the east tonight, allowing moderate to locally strong northeast trades to hold through tonight. This afternoon ASCAT pass showed borderline Small Craft Advisory (SCA) conditions around Maui County and the Big Island leading to less confidence that SCA conditions will hold as the trough passes over the state Thursday, thus have not extended the SCA at this time. After the trough moves through the state Thursday into Friday, a surface high far northeast of the state could allow moderate to locally strong trades to return over the weekend through the forecast period. Above normal moisture and upper level support will allow isolated thunderstorms with localized heavy rain and gusty outflows to develop over the offshore waters tonight through Saturday.
A series of long to medium period south-southwest to south swells will continue fill tonight. Surf along south facing shores should begin to see more consistent sets tonight into Thursday as build to near average. A reinforcing southerly swell will fill in Friday bumping surf near High Surf Advisory thresholds by this weekend as swells shift more out of a south direction.
Surf along east- facing shores increases today into Thursday as trade winds strengthen and a small, medium- period east swell from the remnants of Norbert arrives. Flat to tiny surf along north facing shores is expected through the forecast period.

Fire weather

Issued at 400 PM HST Wed Sep 16 2026
Fire weather risk should remain low through the remainder of the week due to moderate to breezy winds and increased relative humidity and moisture from the remnants of Norbert. Showers will dramatically increase late tonight through early Friday. Inversion heights will be around 7,500 to 8,500 ft.

HFO Watches/Warnings/Advisories

Flood Watch through late Thursday night for Big Island East, Big Island Interior, Big Island North, Big Island South, Big Island Southeast, Big Island Summits, Central Oahu, East Honolulu, Ewa Plain, Haleakala Summit, Honolulu Metro, Kahoolawe, Kauai East, Kauai Mountains, Kauai North, Kauai South, Kauai Southwest, Kipahulu, Kohala, Kona, Koolau Leeward, Koolau Windward, Lanai Leeward, Lanai Mauka, Lanai South, Lanai Windward, Maui Central Valley North, Maui Central Valley South, Maui Leeward West, Maui Windward West, Molokai Leeward South, Molokai North, Molokai Southeast, Molokai West, Molokai Windward, Niihau, Oahu North Shore, Olomana, South Haleakala, South Maui/Upcountry, Waianae Coast, Waianae Mountains, Windward Haleakala.
Small Craft Advisory until 6 AM HST Thursday for Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters, Maalaea Bay, Pailolo Channel.

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Data Courtesy of NOAA.gov