West Kaua’i

Tonight: Mostly clear. Isolated showers in the evening. Lows around 74 near the shore to around 65 above 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Tuesday: Sunny. Isolated showers in the afternoon. Highs 85 to 92 near the shore to around 78 above 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Tuesday Night: Partly cloudy with isolated showers. Lows around 74 near the shore to around 64 above 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

South Kaua’i

Tonight: Breezy. Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 72 to 77. Northeast winds 15 to 20 mph. Chance of rain 40 percent.

Tuesday: Mostly sunny with isolated showers. Highs 80 to 90. East winds 10 to 15 mph. Chance of rain 20 percent.

Tuesday Night: Mostly cloudy with scattered showers. Lows 71 to 77. Northeast winds 10 to 15 mph. Chance of rain 30 percent.

Kaua’i Mountains

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

Tuesday: Mostly sunny with isolated showers. Highs 75 to 83 in the valleys to around 68 above 4000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Tuesday Night: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows around 69 in the valleys to around 62 above 4000 feet. East winds around 10 mph. Chance of rain 40 percent.

North Kaua’i

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

Tuesday: Mostly sunny with isolated showers. Highs 72 to 88. East winds up to 15 mph. Chance of rain 20 percent.

Tuesday Night: Partly cloudy with scattered showers. Lows 65 to 75. East winds around 10 mph. Chance of rain 40 percent.

East Kaua’i

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 68 to 77. East winds 10 to 15 mph. Chance of rain 50 percent.

Tuesday: Mostly sunny with isolated showers. Highs 79 to 87. East winds 10 to 15 mph. Chance of rain 20 percent.

Tuesday Night: Mostly cloudy with scattered showers. Lows 67 to 76. East winds 10 to 15 mph. Chance of rain 40 percent.

Detailed Forecast

Synopsis

Light showers are possible through this evening. Trade wind pattern returns Tuesday with windward and mauka showers much of this week. Precipitation chances increase Friday and Saturday for windward areas. Winds may veer southeasterly late in the week.

Discussion

Scattered, light showers will diminish this evening. Over the past 12 hours an additional 0.20 to 0.60 inches of rain has fallen across the state, with some locally higher accumulations. For the middle of the week, the atmosphere will gradually dry out in the wake of Tropical Storm Lala. Moderate strength winds will prevail for the first half of the week, becoming light by Thursday. The return of the trade winds will maintain scattered showers over windward and mauka locations, with isolated spill over into leeward areas.
For late Thursday through the weekend the trades will veer east- southeast, pulling additional moisture into the area. This will increase precipitable water values for Friday and Saturday. Due to the expected moisture increase, precipitation chances have been increased for Friday into Saturday, especially for windward areas. A subtle drying is expected on Sunday.
For early next week, there is quiet a bit of difference between the GFS and the ECMWF. The GFS supports a wetter pattern with the ECMWF on the drier side. Current forecast maintains drier conditions, which may need adjusting in the coming days depending on how the pattern develops.

Aviation

A ridge of high pressure north of the state will maintain breezy easterly trades through Tuesday. Lingering moisture from Tropical Cyclone Lala continues to produce low/mid-level clouds over the eastern half of the state. Light to moderate showers focused over windward and mauka slopes are generating localized MVFR conditions, with VFR elsewhere. Shower coverage will increase overnight for windward and mauka areas before drier, typical trade wind conditions return Tuesday.
AIRMET Sierra remains in effect for mountain obscurations along windward portions of Kauai Oahu and the Big Island, as well the kona slopes of the Big Island due to sea breezes. AIRMET Sierra may need to be expanded to other islands overnight into Tuesday morning as windward and mauka showers increase.

Marine

With Tropical Storm Lala now well west of the islands, fresh to locally strong easterly trade winds have prevailed across the region today. A Small Craft Advisory (SCA) remains in effect for the windier waters and channels around Maui County and the Big Island through tonight, but trade winds will gradually ease dropping into the moderate to locally breezy range by Tuesday. During the second half of the week, trades will weaken further to become light and variable for most waters before strengthening again this weekend.
Surf along south facing shores remains elevated from a moderate, medium to long period swell that filled in last night. Observations at PacIOOS buoy Barber's Point shows the south swell maintaining at roughly 4 feet, 14 seconds this afternoon. Based on the buoy readings and surf observations from lifeguards and webcams around the state, have adjusted south shore surf up slightly from the previous forecast for this evening. However, it is still expected to slowly decline through midweek, so the overall trend remains unchanged. Some wrap also continues this evening for west facing shores, but this is also expected to follow suit as the south swell declines. Another long period south swell generated from gales just south and east of New Zealand will begin arriving late this week.
Surf along east facing shores will continue to fade tonight as Lala moves further west away from the state and as trades decrease on Tuesday. North facing shores will remain tiny throughout the week.

Fire weather

Issued at 339 PM HST Mon Aug 17 2026 Moderate relatively moist trade winds will prevail through mid-week. Winds will weaken Thursday and Friday with increasing humidity. Trade winds increase over the weekend with minor changes in humidity. No fire weather concerns through the forecast period. There is no temperature inversion.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Tuesday for Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters, Maalaea Bay, Pailolo Channel.

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Data Courtesy of NOAA.gov