West Kaua’i

Tonight: Partly cloudy. Breezy. Isolated showers after midnight. Lows 69 to 74 near the shore to around 62 above 3000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Monday: Mostly sunny with isolated showers. Highs 85 to 91 near the shore to around 76 above 3000 feet. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Monday Night: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 69 to 74 near the shore to around 62 above 3000 feet. Northeast winds 10 to 15 mph decreasing to up to 10 mph after midnight. Chance of rain 50 percent.

South Kaua’i

Tonight: Breezy. Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows around 73. Northeast winds 10 to 20 mph. Chance of rain 40 percent.

Monday: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 80 to 88. Northeast winds 10 to 20 mph. Chance of rain 40 percent.

Monday Night: Mostly cloudy with scattered showers. Lows around 72. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Kaua’i Mountains

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 64 to 69 in the valleys to around 59 above 4000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Monday: Breezy. Partly sunny with scattered showers. Highs 74 to 83 in the valleys to around 66 above 4000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows 64 to 69 in the valleys to around 59 above 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

North Kaua’i

Tonight: Mostly cloudy with scattered showers. Lows 65 to 73. East winds 10 to 15 mph. Chance of rain 50 percent.

Monday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 76 to 87. East winds 10 to 15 mph. Chance of rain 40 percent.

Monday Night: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows 65 to 73. East winds 10 to 15 mph. Chance of rain 60 percent.

East Kaua’i

Tonight: Mostly cloudy with scattered showers. Lows 65 to 76. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Monday: Partly sunny with scattered showers. Highs 73 to 85. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows 64 to 76. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Detailed Forecast

Update

Wind Advisory for Maui County and the Big Island has been cancelled. Winds have dropped below advisory thresholds but will continue to remain breezy through Monday.

Synopsis

Strong trade winds will gradually weaken over the next several days with moderate trades expected by the middle of the week. Passing showers should increase starting tonight and will mainly be focused over windward and mauka areas with light rainfall amounts. The one exception is over on Kauai, where we could see bands of showers move in Monday night through the middle of the week. Light to moderate rainfall will be possible over windward Kauai during this time.

Prev discussion

Wind Advisory remains in effect through this evening, but the latest wind observations are starting to show a slow downward trend. As long as the winds continue to weaken this afternoon, the plan is to cancel the Wind Advisory across Maui and the Big Island over the next few hours.
Mostly dry conditions with strong trades this afternoon will slowly moderate over the next few days as the trades slowly weaken Monday into the middle of the week and showers begin to increase starting tonight. This afternoon's radar and satellite imagery shows stable stratocumulus clouds across many windward and mountain areas with very little rainfall across the state. Upstream of the state, there is a pocket of cumulus clouds which should bring an uptick of showers tonight especially over windward areas of Maui and the Big Island. Rainfall amounts should remain mostly light, but any amounts of rain during the summer time should be beneficial. Monday looks to be a breezy trade wind day with some passing showers over windward and mountain areas in the morning, giving way to partly sunny skies and some scattered showers in the afternoon.
Going into Tuesday, a weak upper level trough will pass near the state, which could enhance the trade wind showers particularly near Kauai Monday night into Tuesday and possibly through Wednesday. Moisture and some weak instability will be greatest near Kauai, which should allow for some periods of moderate rain. No significant impacts are expected, but the showers could be frequent enough to alter your outdoor plans especially over windward and mountain areas of Kauai. For rest of the state, the shower activity is not expected to be as frequent as Kauai, but some passing showers are expected through at least the middle of the week.
In the long range, the weak upper level trough should move westward and away from Kauai by Thursday with an upper level ridge building in from east. Drier conditions will be possible towards the end of the week, but some light passing showers will likely continue to ride in with the moderate to locally breezy trade winds.

Aviation

Strong high pressure to the far northeast of the state will maintain breezy to locally windy trades across the island chain through this evening. With a stable airmass overhead, shower activity has been minimal today, but a steady stream of low level clouds occasionally brought MVFR conditions to windward areas. Overnight, an uptick in low level moisture and instability will bring a greater chance for clouds and showers from east to west across the state, with the best chance for MVFR conditions across windward areas of the Big Island and Maui. The high to our northeast will weaken slightly, but still maintain breezy conditions through the day tomorrow.
AIRMET Tango is in effect for moderate turbulence below 6000 feet downwind of island terrain. This AIRMET will likely be needed through at least tomorrow with the breezy trades.
AIRMET Sierra may be needed overnight for mountain obscuration for windward portions of the Big Island and Maui.

Marine

High pressure NE of the islands will drive strong trades through Monday before weakening during the remainder of the week. The Small Craft Advisory remains in place as is through tomorrow.
Surf along S shores will remain small through early Monday until a moderate, long period south swell starts filling in. Due to recent observations in Samoa this past Friday, the swell is expected to reach near High Surf Advisory criteria as it peaks on Tuesday before declining Wednesday.
Surf along east facing shores will remain rough and choppy through the week. Surf along north facing shores will remain tiny with mainly background energy through the forecast period.
Peak high tides associated with the lunar cycle will lead to minor coastal flooding along shorelines and low lying coastal areas through the week. Coastal flooding will coincide with the daily peak tide each afternoon and may be exacerbated by the ongoing south swell as it peaks on Tuesday.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Monday for Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Windward Waters, Big Island Leeward Waters, Big Island Southeast Waters.

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