West Kaua’i

Rest Of Tonight: Mostly cloudy late in the evening then becoming partly cloudy. Scattered showers late in the evening, then isolated showers after midnight. Lows around 68 near the shore to around 58 above 3000 feet. Light winds becoming northeast up to 10 mph after midnight. Chance of rain 40 percent.

Monday: Mostly sunny. Isolated showers in the morning. Highs around 81 near the shore to around 70 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Monday Night: Clear. Lows around 67 near the shore to around 57 above 3000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph after midnight.

South Kaua’i

Rest Of Tonight: Mostly cloudy late in the evening then becoming partly cloudy. Scattered showers. Lows around 67. Northeast winds 10 to 15 mph. Chance of rain 30 percent.

Monday: Mostly sunny. Breezy. Isolated showers in the morning. Highs 76 to 82. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Monday Night: Clear. Lows around 67. Northeast winds around 15 mph.

Kaua’i Mountains

Rest Of Tonight: Mostly cloudy with scattered showers. Lows 60 to 66 in the valleys to around 56 above 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Monday: Partly sunny. Breezy. Isolated showers in the morning. Highs 70 to 76 in the valleys to around 61 above 4000 feet. Northeast winds up to 15 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 20 percent.

Monday Night: Mostly clear. Breezy. Lows 59 to 65 in the valleys to around 55 above 4000 feet. Northeast winds 10 to 20 mph.

North Kaua’i

Rest Of Tonight: Mostly cloudy with scattered showers. Lows 61 to 69. East winds up to 10 mph. Chance of rain 40 percent.

Monday: Partly sunny. Isolated showers in the morning. Highs 72 to 81. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Monday Night: Clear. Lows 60 to 68. Northeast winds 10 to 15 mph.

East Kaua’i

Rest Of Tonight: Mostly cloudy with scattered showers. Lows 62 to 71. North winds around 10 mph. Chance of rain 50 percent.

Monday: Mostly sunny with isolated showers in the morning, then partly sunny in the afternoon. Highs 69 to 79. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Monday Night: Mostly clear. Lows 61 to 71. Northeast winds 10 to 15 mph.

Detailed Forecast

Synopsis

The kona low that produced significant heavy rain, thunderstorms and flash flooding over the Hawaiian Islands over the past four days continues to move rapidly towards the northeast away from the state. An upper level subtropical jet stream and deep unstable band of tropical moisture lingers over the eastern half of the state. This larger scale moisture band will drift eastward through Monday as high pressure builds in from the northwest, allowing more stabilizing trade winds to spread southeastward down the island chain. These cooler moderate to locally breezy trade winds will lower humidity levels and continue blowing across the islands through next weekend with passing showers favoring windward and mountain areas.

Short term update

Trade winds have returned to Kauai and portions of Oahu this evening based on surface weather observation reports. The kona low that produced significant heavy rain, thunderstorms and flash flooding over the Hawaiian Islands over the past four days is roughly 1,200 miles north of the Big Island and continues to move rapidly towards the northeast at 30 MPH away from the state.
The satellite water vapor channel imagery this evening shows a band of deep tropical moisture under the divergent influence of the Sub Tropical Jet lingering over the eastern half of the state. A large are of more stable, subsiding air, continues to drift into the region from the northwest as the high pressure ridge builds in behind the departing kona low. Local scale radar and satellite analysis reveals bands of moderate to heavy rain showers and a few thunderstorms continuing to develop over the coastal waters near the Big Island tonight. These developing shower bands may continue to produce some additional rainfall over the Big Island through Monday morning. Based on these short term weather trends the Flood Watch for the islands in Maui County was cancelled this evening.
The latest short range weather models show the frequency of these developing shower bands will decline on Monday over the Big Island as stabilizing trade winds spread southeastward to all islands by Monday afternoon. That said, a Flood Watch remains in effect through Monday morning for Hawaii County to address the potential threat from any developing smaller scale (mesoscale) heavy shower bands or thunderstorms. Unless conditions change we will likely cancel the Flood Watch for all islands with the Monday morning forecast package.

Previous discussion

Issued at 319 PM HST Sun Mar 22 2026
The kona low will move away to the northeast tonight while the remnant band of moisture covering Oahu to the Big Island stays in place through Monday night. An upper trough moving towards the islands will keep enhanced showers and isolated thunderstorms going into the morning across Maui County and Big Island, and Oahu to a lesser extent. Therefore, will extend the Flood Watch for Maui County and Big Island through the night. The Winter Storm Warning for the Big Island summits will also continue with a few more inches of snow expected above 12000 feet. Numerous, but lighter showers will continue across Maui County and Big Island on Monday.
Trade winds will begin filling in Monday west to east, reaching the Big Island by Tuesday. Once the trades arrive, the leftover clouds and showers from the kona low will shift into a more typical trade wind distribution, favoring windward and mauka areas and much lighter than during the event itself. The moisture clears the islands by Wednesday with drier trade wind weather expected into next weekend.

Aviation

Residual moisture from the departing kona low has left showers with embedded isolated thunderstorms across much of the Hawaiian Islands, namely from Oahu to the Big Island. Periods of MVFR conditions in these showers, with local LIFR conditions possible. Otherwise, first indication of trades have returned across the western islands and will spread across the state throughout the forecast period. VFR conditions prevail otherwise.
AIRMET Sierra is in effect for Lanai due to IFR in widespread low ceilings and showers and is expected to continue into tonight. AIRMET Sierra is also in effect for Oahu, Maui, Molokai, and the Big Island for mountain obscuration due to showers and low clouds. This is also expected to continue into tonight.
AIRMET Zulu remains for light icing in layer 140-FL260 will also persist, mainly over the central portion of the state where the thick high clouds continue to stream over from the southwest.

Marine

Issued at 319 PM HST Sun Mar 22 2026
Bands of scattered moderate to heavy showers, with an occasional embedded thunderstorm, moving in from the south will primarily impact those waters surrounding Maui County and Big Island. A boundary northwest of the island chain will travel southeast across the state through Monday. Gentle variable to southerly breezes downstream of this boundary will transition to strengthened north northeast winds behind the boundary passage. Moderate trades will become better established early this week, along with widely- scattered light showers, as the upper trough passes east of the state Tuesday.
The northeast swell that peaked yesterday will be on the decline through Monday. A small north swell will reinforce an already established background north swell Tuesday and Wednesday. This will maintain elevated north-facing shore surf the next few days. Very small south southwest swell will keep south-facing shore surf from going completely flat the remainder of the week. East surf will stay slightly elevated through Monday as result of a fading northeast swell and a little north wrap. East-facing shore short period wind waves will pick up at mid week in response to strengthened trades.

HFO Watches/Warnings/Advisories

Flood Watch until 6 AM HST Monday for the Big Island of Hawaii.
Winter Storm Warning until 6 AM HST Monday for Big Island Summits of Mauna Kea and Mauna Loa.

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Data Courtesy of NOAA.gov