West Kaua’i

Tonight: Mostly clear. Lows around 67 near the shore to around 57 above 3000 feet. East winds up to 10 mph.

Monday: Mostly sunny. Isolated showers in the afternoon. Highs 78 to 86 near the shore to around 72 above 3000 feet. East winds up to 10 mph shifting to the south in the afternoon. Chance of rain 20 percent.

Monday Night: Partly cloudy with isolated showers. Lows around 67 near the shore to around 57 above 3000 feet. Light winds. Chance of rain 20 percent.

South Kaua’i

Tonight: Partly cloudy. Isolated showers after midnight. Lows around 67. Northeast winds around 10 mph. Chance of rain 20 percent.

Monday: Mostly sunny. Isolated showers in the morning. Highs 77 to 84. Northeast winds around 10 mph shifting to the southeast up to 10 mph in the afternoon. Chance of rain 20 percent.

Monday Night: Partly cloudy with isolated showers. Lows around 67. Light winds. Chance of rain 20 percent.

Kaua’i Mountains

Tonight: Partly cloudy. Isolated showers after midnight. Lows 57 to 67 in the valleys to around 55 above 4000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Monday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 73 to 79 in the valleys to around 64 above 4000 feet. Light winds. Chance of rain 30 percent.

Monday Night: Partly cloudy. Lows 57 to 67 in the valleys to around 56 above 4000 feet. Light winds becoming north around 10 mph after midnight.

North Kaua’i

Tonight: Mostly clear. Isolated showers after midnight. Lows 60 to 68. Southeast winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Monday: Mostly sunny. Isolated showers in the afternoon. Highs 73 to 81. Southeast winds up to 10 mph. Chance of rain 20 percent.

Monday Night: Partly cloudy. Lows 60 to 68. Light winds.

East Kaua’i

Tonight: Partly cloudy. Isolated showers after midnight. Lows 60 to 71. Northeast winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Monday: Mostly sunny with isolated showers. Highs 72 to 83. Light winds becoming southeast up to 10 mph in the afternoon. Chance of rain 20 percent.

Monday Night: Partly cloudy with isolated showers. Lows 60 to 70. Light winds. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Light to moderate winds and mostly dry conditions will prevail through Tuesday, with a few showers possible along windward slopes and coasts at night and over the island interiors each afternoon. A cold front will approach from the northwest Wednesday and Thursday, shifting winds more southerly and bringing an uptick of showers, particularly over the western end of the state. The front should lift northward on Friday, with some lingering moisture keeping some scattered shower activity in place over the western islands.

Discussion

A front developing far northwest of the state tonight and passing north of the state Monday night into Tuesday will cause the ridge of high pressure to shift southeast and closer to the state. This will cause the trade winds to weaken and veer toward the southeast tonight into Monday. For tonight with the trade winds weakening, we should see land breezes develop in many areas, which produce mostly dry conditions across the state.
A hybrid trade wind/sea breeze pattern is expected on Monday with light to moderate east to southeast winds across the state. Sea breezes are expected to develop by mid day with afternoon clouds and a few light showers developing over interior and leeward areas. As the front passes northeast of the area on Tuesday, a high building north of the area will produce a light northerly flow Tuesday morning becoming more northeast throughout the day. Moderate northeast trades are expected by Tuesday afternoon with some isolated windward and mauka showers. Rainfall amounts with any showers will continue to remain light due to stable conditions aloft.
Starting Wednesday, a stronger front will approach the state and will cause the winds to veer toward the south. With light to moderate southerly winds in place, passing showers will be on the increase especially over the western half of the state. Stable conditions aloft will continue to limit rainfall intensity, but with the increase of some low level moisture, we could see some brief moderate showers Thursday through Friday. In summary, stable conditions will continue the second half of the week, but with the winds out of the south, we should see warmer weather (higher humidities) with an uptick of showers especially the western half of the state.
Over the weekend, a ridge of high pressure is expected to move over the state which should produce a light wind pattern with stable conditions. Expect sea breezes to develop during the day with afternoon clouds and a few light showers. Land breezes should develop during the evening, which will help clear any clouds and showers during the overnight hours.

Aviation

The ridge of high pressure just north of the island chain will serve to deflect an incoming cold front moving in from the northwest. The ridge is expected to hold through forty-eight hours and beyond, keeping the air mass mostly dry and mostly stable.
Light trade winds will steer occasional bands of clouds and showers towards windward slopes and coasts. In the afternoons and early evenings, local sea breezes will encourage cumulus development over island interiors.
No AIRMETs are in effect or anticipated at this time.

Marine

A ridge of high pressure north of the islands will maintain light to moderate trade winds into Monday. A front to the northwest will pass north of the islands on Monday, which will push the ridge over the islands, resulting in a weakening of the winds Monday and into Monday night. Behind the front, a short period of east to east-southeast trades are expected Tuesday and Tuesday night, before winds shift out of the south ahead of another front approaching from the northwest Wednesday. This front should lift northward on Friday.
The current west-northwest swell (310 degrees) is expected to peak over the next few hours, and then subside overnight, with surf expected to fall below High Surf Advisory levels by daybreak Monday. A Small Craft Advisory is also in effect for hazardous seas in excess of 10 feet through daybreak Monday for waters exposed to this swell. The swell will slowly lower through the first part of the week. A similar sized northwest swell is expected to build in late Tuesday and linger through Wednesday, resulting in peak surf heights above advisory levels for north and west facing shores. A larger northwest swell is then possible towards the end of the week. Small surf is expected along south and east facing shores.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 AM HST Monday for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Maui Windward West, Kauai North, Molokai Windward, Molokai North, Molokai West, Maui Central Valley North, Windward Haleakala.
Small Craft Advisory until 6 AM HST Monday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Oahu Windward Waters, Maui County Windward Waters.

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