Hilo

Today: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 83 near the shore to 68 to 73 at 4000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 68 near the shore to around 54 at 4000 feet. North winds up to 15 mph. Chance of rain 50 percent.

Wednesday: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 83 near the shore to 68 to 73 at 4000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Kona

Today: Mostly sunny in the morning then becoming mostly cloudy. Isolated showers. Highs 81 to 86 near the shore to around 68 near 5000 feet. Southwest winds up to 10 mph shifting to the west in the afternoon. Chance of rain 20 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows 69 to 75 near the shore to around 55 near 5000 feet. Light winds. Chance of rain 20 percent.

Wednesday: Mostly sunny in the morning then becoming mostly cloudy. Isolated showers. Highs 81 to 86 near the shore to around 68 near 5000 feet. West winds up to 10 mph. Chance of rain 20 percent.

Waimea

Today: Breezy. Partly sunny with isolated showers. Highs around 81 near the shore to 68 to 78 near 3000 feet. East winds 10 to 25 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with isolated showers. Lows around 68 near the shore to 56 to 62 near 3000 feet. East winds 10 to 25 mph. Chance of rain 20 percent.

Wednesday: Breezy. Partly sunny with isolated showers. Highs around 81 near the shore to 68 to 78 near 3000 feet. East winds 10 to 25 mph. Chance of rain 20 percent.

Kohala

Today: Breezy. Partly sunny with isolated showers. Highs around 81 near the shore to 68 to 78 near 3000 feet. East winds 10 to 25 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with isolated showers. Lows around 68 near the shore to 56 to 62 near 3000 feet. East winds 10 to 25 mph. Chance of rain 20 percent.

Wednesday: Breezy. Partly sunny with isolated showers. Highs around 81 near the shore to 68 to 78 near 3000 feet. East winds 10 to 25 mph. Chance of rain 20 percent.

South Big Island

Today: Mostly sunny. Breezy. Highs around 85 near the shore to around 72 near 5000 feet. East winds 10 to 20 mph decreasing to up to 20 mph in the afternoon.

Tonight: Partly cloudy. Lows around 70 near the shore to around 53 near 5000 feet. Northeast winds up to 15 mph.

Wednesday: Mostly sunny. Breezy. Highs around 85 near the shore to around 72 near 5000 feet. East winds up to 20 mph.

Puna

Today: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 83 near the shore to 68 to 73 at 4000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 68 near the shore to around 54 at 4000 feet. North winds up to 15 mph. Chance of rain 50 percent.

Wednesday: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 83 near the shore to 68 to 73 at 4000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Waikoloa

Today: Mostly sunny. Highs around 85 near the shore to 69 to 75 above 4000 feet. North winds up to 15 mph.

Tonight: Mostly clear. Lows 70 to 75 near the shore to 51 to 58 above 4000 feet. Southeast winds up to 15 mph.

Wednesday: Mostly sunny. Breezy. Highs around 85 near the shore to 69 to 75 above 4000 feet. Northeast winds up to 20 mph.

Detailed Forecast

Update

The forecast has been updated to include a Wind Advisory for the Big Island Summits through 6 PM HST this evening.

Synopsis

Breezy trade winds will continue through midweek, then ease from Thursday into the weekend as the surface ridge weakens to the north. A dry airmass will limit rainfall chances through much of the week, with the best chances remaining over windward and mauka locations overnight through the morning periods. A slight increase in moisture associated with a mid- to upper-level disturbance could lead to better shower coverage later in the week and into the upcoming weekend.

Discussion

Short-term guidance shows dry trade wind conditions prevailing through midweek as a deep layer ridge remains in place. The overnight upper air soundings reflect this pattern, showing strong subsidence inversions around 5,000 to 6,000 ft with limited moisture available. Any brief showers that form will favor the typical windward and mauka locations, primarily during the overnight and early morning periods.
The mid- to upper-level ridge will begin to weaken during the second half of the week and into the upcoming weekend as a weak upper low settles north of Kauai and a mid-level trough approaches from the east. The surface ridge will respond by weakening, resulting in the trades easing to light to moderate levels. Upper-level height falls combined with increasing low-level moisture could lead to better windward shower coverage, especially over the weekend as the mid-level trough moves through from east to west. Additionally, a few showers could form over dry leeward areas during the afternoon where localized sea breezes develop.

Aviation

Moderate to locally breezy trades are expected through Wednesday. Mostly VFR conditions will prevail with brief periods of MVFR possible in the overnight to early morning hours along windward and mountain slopes.
AIRMET Sierra remains in effect for tempo mountain obscuration over north and east sections of Maui and the Big Island.
AIRMET Tango remains in effect for moderate turbulence over and immediately south through west of all island mountains due to the breezy trade winds.

Marine

A surface ridge north of the state will support moderate to locally strong trade winds through midweek. The ridge may weaken somewhat thereafter, with trade wind speeds slowly diminishing in response. A Small Craft Advisory (SCA) is posted for the typical windy waters around Maui and the Big Island through Wednesday. As the trades ease during the second half of the week, seas will also subside, and the SCA will go away.
The medium-period S swell of the past several days will trend lower today. Surf should return to background levels by Thursday along south facing shores. A small, longer period SSW swell should fill in on Friday and peak over the weekend with surf heights near or slightly above the summer average.
A small, short-period NNW swell will decline tonight into Tuesday night. Another small, short-period NNW swell may arrive around Thursday. Short-period wind waves will support small to moderate surf along E facing shores through Wednesday. Small, long-period E swells from increased E Pacific tropical cyclone activity may arrive (low confidence) from Wednesday onward, leading to a subtle increase in surf heights.

HFO Watches/Warnings/Advisories

Wind Advisory until 6 PM HST this evening for Big Island Summits.
Small Craft Advisory until 6 PM HST Wednesday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov