Photo Credit: Tyler Rooke

West Side

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 81 to 88. East winds up to 15 mph. Chance of rain 40 percent.

Tonight: Partly cloudy with scattered showers. Lows 67 to 74. East winds up to 15 mph. Chance of rain 50 percent.

Monday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 81 to 88. East winds up to 15 mph. Chance of rain 50 percent.

South Side

Today: Sunny. Highs 85 to 90. North winds 10 to 15 mph shifting to the northeast in the afternoon.

Tonight: Mostly clear. Isolated showers in the evening. Lows around 68. North winds up to 10 mph. Chance of rain 20 percent.

Monday: Sunny. Highs 85 to 90. North winds up to 15 mph.

North Shore

Today: Partly sunny. Breezy. Occasional showers in the morning, then scattered showers in the afternoon. Highs 80 to 86 near the shore to around 67 near 5000 feet. East winds up to 20 mph. Chance of rain 80 percent.

Tonight: Mostly cloudy with numerous showers. Lows 64 to 71 near the shore to around 52 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 70 percent.

Monday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 80 to 86 near the shore to around 67 near 5000 feet. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 70 percent.

Central Maui

Today: Mostly sunny with isolated showers. Highs around 88. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with scattered showers. Lows 66 to 72. East winds up to 15 mph. Chance of rain 40 percent.

Monday: Breezy. Mostly sunny with isolated showers. Highs around 88. Northeast winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 20 percent.

Upcountry

Today: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 63 at the visitor center to around 60 at the summit. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with isolated showers in the evening, then partly cloudy with scattered showers after midnight. Lows around 46 at the visitor center to around 42 at the summit. East winds up to 15 mph. Chance of rain 50 percent.

Monday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 63 at the visitor center to around 60 at the summit. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

East Maui

Today: Partly sunny. Breezy. Occasional showers in the morning, then scattered showers in the afternoon. Highs 80 to 86 near the shore to around 67 near 5000 feet. East winds up to 20 mph. Chance of rain 80 percent.

Tonight: Mostly cloudy with numerous showers. Lows 64 to 71 near the shore to around 52 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 70 percent.

Monday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 80 to 86 near the shore to around 67 near 5000 feet. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 70 percent.

Lanai City

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 74 to 83. Northeast winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows around 66. East winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Monday: Partly sunny with scattered showers. Highs 74 to 83. Light winds becoming northeast up to 10 mph in the afternoon. Chance of rain 40 percent.

Kaunakakai

Today: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 82 to 89. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 67 to 77. East winds 10 to 15 mph decreasing to up to 10 mph after midnight. Chance of rain 50 percent.

Monday: Mostly sunny with isolated showers. Highs 82 to 89. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Trade winds will decrease through Monday as a surface ridge to our north weakens. Rainfall will favor windward and mauka locations but a few showers, some heavy, may develop across leeward areas as an upper disturbance moves by. Breezy trades and more stable conditions are expected to return on Tuesday.

Discussion

A surface ridge far north of the main Hawaiian Islands is driving moderate trades across local waters this morning. An upper low north of Kauai will dig southward over the next few days, causing the inversion to lift and weaken. As a result, mainly windward showers may become a bit heavier than the past few days. A narrow and diffuse band of moisture in the trades will likely bring higher shower coverage from Maui to Oahu this morning. Expect slightly weaker trades and heavier showers through Monday.
Expect stronger and more stable trade wind flow by midweek. Locally breezy trades will be driven by a tighter pressure gradient between the strengthening surface ridge to the north and a pair of tropical disturbances passing several hundred miles south of the islands. The upper low will fill and drift away to the west, and a ridge aloft building in from the east will bring stability. Models differ on timing but show a pocket of moisture in the building trades passing over the islands late Monday and Tuesday. This will likely be too late for enhanced rainfall and is expected to produce typical windward showers. Through the rest of the work week, tropical moisture could clip the Big Island, but expect typical windward rainfall for most islands.

Aviation

Moderate trade winds with scattered showers favoring windward and mountain areas. As an upper level low approaches from the north today, brief moderate to heavy downpours will occur with some spillover into leeward areas. AIRMET Sierra posted for tempo mountain obscurations above 2500 feet for windward portions of Oahu, Molokai, Maui and Big Island. Brief mountain obscurations, MVFR cig/vis may occur elsewhere within the passing showers.
AIRMET Tango is in effect for tempo moderate turbulence between FL200 and FL400 over the islands tonight. This AIRMET will likely be needed through the morning.

Marine

Fresh trade winds will ease slightly today as a cold front passing through the far northern Central Pacific basin weakens the ridge north of the island chain. Wind speeds will remain below Small Craft Advisory levels through Monday. The trade winds will strengthen back to moderate and locally strong levels from Monday night on through the rest of the week.
Surf along north and west facing shores will remain tiny through Monday. A moderate, long-period northwest swell will arrive on Tuesday and push surf heights along north and west facing shores well above seasonal average, below High Surf Advisory levels, Tuesday night and Wednesday. This swell will decline as it shifts out of the north-northwest on Thursday, then fades on Friday.
Surf along south facing shores will remain just below seasonal average levels as an inconsistent southwest swell moves through the Hawaii region. A reinforcing southwest swell is expected late Monday into Wednesday. As trade winds decline, east shore surf will remain small during the next few days with slight increasing trends by Tuesday night or Wednesday.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov