West Kaua’i

Tonight: Mostly cloudy with isolated showers in the evening, then partly cloudy with scattered showers after midnight. Lows around 71 near the shore to around 61 above 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Saturday: Mostly sunny in the morning then becoming mostly cloudy. Scattered showers. Highs 84 to 90 near the shore to around 76 above 3000 feet. Northeast winds up to 15 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Saturday Night: Mostly cloudy in the evening then becoming mostly clear. Isolated showers. Lows around 71 near the shore to around 62 above 3000 feet. East winds 10 to 15 mph decreasing to up to 15 mph after midnight. Chance of rain 20 percent.

South Kaua’i

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows around 73. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Saturday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 81 to 89. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Saturday Night: Mostly cloudy with scattered showers. Lows around 73. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Kaua’i Mountains

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then occasional showers after midnight. Lows 63 to 69 in the valleys to around 59 above 4000 feet. Northeast winds 10 to 20 mph. Chance of rain 90 percent.

Saturday: Breezy. Mostly cloudy with numerous showers. Highs 74 to 82 in the valleys to around 66 above 4000 feet. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

Saturday Night: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 63 to 69 in the valleys to around 58 above 4000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

North Kaua’i

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 65 to 73. East winds 10 to 15 mph decreasing to up to 15 mph after midnight. Chance of rain 70 percent.

Saturday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 75 to 85. East winds up to 15 mph shifting to the northeast in the afternoon. Chance of rain 70 percent.

Saturday Night: Mostly cloudy with scattered showers. Lows 64 to 73. East winds 10 to 15 mph. Chance of rain 50 percent.

East Kaua’i

Tonight: Mostly cloudy. Scattered showers in the evening, then occasional showers after midnight. Lows 64 to 76. Northeast winds 10 to 15 mph. Chance of rain 90 percent.

Saturday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 73 to 85. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Saturday Night: Mostly cloudy with scattered showers. Lows 64 to 76. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Trade winds will persist through the week and will be breezy and gusty Saturday through Tuesday. Showers will be focused along typical windward and mauka areas, as well as the Kona slopes of the Big Island each afternoon.

Discussion

Rather typical June trade wind conditions are in place. Broad high pressure north of the state is driving moderate to locally breezy trade winds, and a mid-level ridge overhead is producing very stable conditions with an inversion based between 5,000 and 6,500 ft. As a result, modest showers of mostly a quarter of an inch or less have been focused along windward areas since less night, with the highest totals on the Big Island and Maui. Expect minimal windward rainfall today, and aside from scattered afternoon and evening showers along the Kona slopes of the Big Island, leeward areas will be dry. A weak upper-level low centered west of Kauai will send thin high clouds overhead but will otherwise have no impact on local weather today.
An uptick in the trades will occur during the weekend as high pressure builds north of the islands. Breezy and gusty winds will gradually increase Saturday and peak Sunday. Little change in the shower pattern is expected over most islands, though a modest increase in rainfall is possible over Kauai as the above mentioned upper-level low drifts closer.
Trade winds and a typical pattern of mainly windward showers will persist next week. Breezy and gusty trades will hold through Tuesday then drop slightly midweek. Stable conditions will persist with no significant sources of enhanced moisture noted in the guidance.

Aviation

Moderate to breezy trade winds will focus incoming low clouds and showers over windward and mauka areas. Brief MVFR ceilings and visibility may occur overnight along the windward slopes, with the possibility of AIRMET Sierra for tempo mountain obscurations. VFR conditions expected elsewhere through Saturday.
AIRMET Tango is posted for tempo moderate turbulence leeward of mountains across all islands. This will likely continue through the weekend as trade winds strengthen.

Marine

High pressure will build far north of the islands this weekend and will strengthen the trade winds a notch especially Sunday into early next week. A Small Craft Advisory (SCA) for the windier waters and channels around Maui County and the Big Island remains in effect through Sunday, but will likely need to be expanded in coverage and extended as the trades strengthen.
Surf along south facing shores will be small through Saturday. A series of small, long period, south swells originating from fetches near New Zealand will help boost surf heights near the summer average (5 feet) throughout next week. The first boost should fill in Sunday into Monday, followed by another bump Wednesday into Thursday of next week.
Rough and choppy surf along east facing shores are expected to slightly increase this weekend into early next week due to trade winds strengthening. Surf will remain at seasonable levels (nearly flat) along north facing shores throughout the forecast period. Some select exposures could see some tradewind swell wrap.

HFO Watches/Warnings/Advisories

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

Kauai Now Weather is brought to you by Blue Hawaiian Helicopters.