West Kaua’i

Rest Of Tonight: Mostly clear. Breezy. Lows around 76 near the shore to around 66 above 3000 feet. East winds up to 20 mph.

Sunday: Sunny. Highs 88 to 95 near the shore to around 81 above 3000 feet. East winds up to 15 mph.

Sunday Night: Partly cloudy with isolated 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 20 percent.

South Kaua’i

Rest Of Tonight: Breezy. Partly cloudy with isolated showers. Lows 73 to 78. Northeast winds 15 to 20 mph. Chance of rain 20 percent.

Sunday: Breezy. Mostly sunny with isolated showers. Highs 81 to 92. Northeast winds 15 to 20 mph. Chance of rain 20 percent.

Sunday Night: Mostly cloudy with scattered showers. Lows 73 to 78. Northeast winds around 15 mph. Chance of rain 50 percent.

Kaua’i Mountains

Rest Of Tonight: Mostly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows around 72 in the valleys to around 64 above 4000 feet. East winds 10 to 20 mph. Chance of rain 30 percent.

Sunday: Mostly sunny in the morning then becoming partly sunny. Breezy. Isolated showers. Highs 77 to 85 in the valleys to around 71 above 4000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Sunday Night: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows around 71 in the valleys to around 64 above 4000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

North Kaua’i

Rest Of Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 67 to 77. East winds up to 15 mph. Chance of rain 30 percent.

Sunday: Breezy. Mostly sunny with isolated showers. Highs 74 to 91. East winds up to 15 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 20 percent.

Sunday Night: Mostly cloudy with scattered showers. Lows 67 to 76. East winds 10 to 15 mph. Chance of rain 50 percent.

East Kaua’i

Rest Of Tonight: Mostly cloudy with isolated showers. Lows 70 to 79. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Sunday: Breezy. Partly sunny with isolated showers. Highs 81 to 88. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Sunday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 69 to 78. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Trade winds will continue to strengthen today as Tropical Storm Moke moves generally from east to west, south of the islands. This system will deliver periods of rainfall to all islands from late tonight through Monday, with the heaviest rainfall forecast along windward and southeast slopes of the Big Island. A Flood Watch goes into effect for the Big Island at midnight Saturday night. A Wind Advisory is in effect for parts of the Big Island and Maui County through 6 PM HST Sunday. Drier trade wind weather will return Tuesday.

Discussion

Satellite imagery shows Moku weakening this afternoon as dry air and vertical wind shear take a toll. Winds have not officially decreased, but it looks like that may be happening soon. It was centered around 380 miles SE of Hilo as to 3 PM HST. Otherwise, isolated light were moving across northern sections of the Big Island. Other areas were dry. Trade winds were averaging 10 to 20 mph with gusts 20 to 35 mph.
Depending on exactly if or how much Moke weakens over the next 12 or so hours, the surface pressure gradient is expected to tighten up and strengthen winds up to advisory criteria in some areas of Big Island and Maui County. Winds in the lee of the Kohala Mountains may approach wind warning criteria, and winds in the lee of the Ko'olau and Wai'anae mountains on Oahu may approach wind advisory level Sunday. These areas will be watched closely to see how the forecast evolves. Winds are forecast to begin a gradual weakening Sunday night into Monday, and a return to more typical trades is expected by Tuesday.
We have maintained the forecast of rainfall amounts. The latest GFS is trending slightly down, but the EC has trended up. Mesoscale models show a slightly later arrival time. There is sufficient uncertainty to make keeping things steady the most appropriate forecast at this time. Flooding rains remain possible on Big Island. Eastern Maui will be monitored closely. Other areas seem unlikely to experience flooding rains apart from isolated training effects that may develop.
A Flood Watch for the Big Island will go into effect tonight and continue through Monday afternoon. Rainfall totals of 5 to 10 inches, locally up to 15 inches are possible over the windward and southeast slopes of the Big Island. It will not take a significant amount of rain to cause flash flooding due to saturated grounds from recent heavy rain.
Moisture will remain above normal Monday as Moke moves west away from the area. Showers will continue, mainly windward and mauka. By Tuesday, drier air will move in from the east, and typical trade winds/showers are forecast for the remainder of the week.

Aviation

Trade winds will fill back in over the islands as Tropical Storm Moke approaches and passes south of the Big Island this weekend, increasing the pressure gradient across the state. Trades will continue to strengthen from east to west through Sunday.
AIRMET Tango is in effect starting 21Z for low level turbulence downwind of island terrain.
While occasional pockets of MVFR conditions will be possible within passing showers along windward and mauka locations today, VFR conditions are expected to prevail. Tonight into Sunday, increasing moisture over the eastern end of the state as Tropical Storm Moke passes by to our south will result in increasing chances for heavy rainfall, along with low visibilities and ceilings, across the Big Island. This will bring more widespread MVFR and IFR conditions.

Marine

Trades are strengthening in response to Tropical Storm Moke passing south of the islands and the Small Craft Advisory remains in effect through the weekend. Breezy trades then persist well into next week as high pressure remains anchored along 30N.
Surf along E and SE shores gradually builds in response to strengthening trades and short period fresh swell emanating from Tropical Storm Moke. The direction of this swell will transition to S and then SW as Moke advances west. A High Surf Advisory (HSA) may be needed for the SE shores of the Big Island tonight into Sunday, but at this time it appears surf will fall shy of the HSA threshold.
Surf along S shores remains slightly below the summer average but still slightly elevated through the weekend due to a small, long period SW swell. A series of long period S swells arrive during the middle of next week bumping surf to around the advisory threshold.
A small medium to long period NW swell originating from Hurricane Lala provides elevated surf along N and W shores this weekend.

Fire weather

Issued at 319 PM HST Sat Aug 22 2026
Trade winds continue to increase tonight. The inversion will steadily weaken and erode as deep moisture associated with TS Moke moves into the area tonight into Sunday. Heavy rain is expected over windward and SE facing slopes of the Big Island on Sunday.

HFO Watches/Warnings/Advisories

Wind Advisory until 6 PM HST Sunday for Big Island Interior, Big Island North, Big Island South, Big Island Southeast, Kahoolawe, Kohala, Lanai Leeward, Lanai Mauka, Lanai Windward, Maui Central Valley North, Maui Central Valley South, Maui Leeward West, Molokai Leeward South, Molokai North, Molokai Southeast, Molokai West, South Haleakala, Windward Haleakala.
Flood Watch from midnight HST tonight through Monday afternoon for Big Island East, Big Island Interior, Big Island North, Big Island South, Big Island Southeast, Big Island Summits, Kohala, Kona.
Small Craft Advisory until 6 PM HST Sunday for Kauai Channel, Kauai Leeward Waters, Kauai Northwest Waters, Kauai Windward Waters.
Small Craft Advisory until 6 PM HST Sunday for Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters, Big Island Windward Waters, Kaiwi Channel, Maalaea Bay, Maui County Leeward Waters, Maui County Windward Waters, Oahu Leeward Waters, Oahu Windward Waters, Pailolo Channel.

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Data Courtesy of NOAA.gov