Hilo

Today: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs around 82 near the shore to 65 to 70 at 4000 feet. East winds up to 10 mph. Chance of rain 40 percent.

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows around 64 near the shore to around 50 at 4000 feet. Light winds becoming southeast up to 10 mph after midnight. Chance of rain 30 percent.

Monday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs around 81 near the shore to 65 to 70 at 4000 feet. Southeast winds up to 10 mph. Chance of rain 50 percent.

Kona

Today: Mostly sunny. Scattered showers in the afternoon. Highs 80 to 85 near the shore to around 71 near 5000 feet. West winds up to 10 mph. Chance of rain 40 percent.

Tonight: Partly cloudy with isolated showers. Lows 64 to 71 near the shore to around 51 near 5000 feet. Light winds. Chance of rain 20 percent.

Monday: Mostly sunny. Scattered showers in the afternoon. Highs 80 to 85 near the shore to around 71 near 5000 feet. Northwest winds up to 10 mph. Chance of rain 40 percent.

Waimea

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 81 near the shore to 71 to 78 near 3000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 63 near the shore to 49 to 57 near 3000 feet. East winds up to 10 mph. Chance of rain 30 percent.

Monday: Mostly sunny with scattered showers. Highs around 80 near the shore to 71 to 78 near 3000 feet. East winds up to 10 mph. Chance of rain 40 percent.

Kohala

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 81 near the shore to 71 to 78 near 3000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 63 near the shore to 49 to 57 near 3000 feet. East winds up to 10 mph. Chance of rain 30 percent.

Monday: Mostly sunny with scattered showers. Highs around 80 near the shore to 71 to 78 near 3000 feet. East winds up to 10 mph. Chance of rain 40 percent.

South Big Island

Today: Breezy. Mostly sunny with isolated showers. Highs around 83 near the shore to around 72 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers after midnight. Lows around 66 near the shore to around 50 near 5000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Monday: Mostly sunny with isolated showers. Highs around 83 near the shore to around 72 near 5000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Puna

Today: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs around 82 near the shore to 65 to 70 at 4000 feet. East winds up to 10 mph. Chance of rain 40 percent.

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows around 64 near the shore to around 50 at 4000 feet. Light winds becoming southeast up to 10 mph after midnight. Chance of rain 30 percent.

Monday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs around 81 near the shore to 65 to 70 at 4000 feet. Southeast winds up to 10 mph. Chance of rain 50 percent.

Waikoloa

Today: Mostly sunny. Isolated showers in the afternoon. Highs around 82 near the shore to 66 to 73 above 4000 feet. South winds up to 10 mph shifting to the northwest in the afternoon. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers after midnight. Lows 66 to 71 near the shore to 46 to 54 above 4000 feet. Light winds. Chance of rain 20 percent.

Monday: Mostly sunny. Isolated showers in the afternoon. Highs around 82 near the shore to 66 to 73 above 4000 feet. Light winds. Chance of rain 20 percent.

Detailed Forecast

Synopsis

A ridge north of the area will shift southward over the next few days as a front approaches from the northwest. The front will dissipate north of the area Monday and Tuesday. An upper trough will pass over the area late Wednesday through Thursday night. High pressure will begin to build back in northwest of the area Friday and Saturday.

Discussion

A high far northeast of the area has an associated ridge extending westward to a position several hundred miles north of the main Hawaiian Islands, driving moderate east to east southeast winds across local waters this morning. An upper ridge keeps our airmass rather stable, with inversion heights near 5000 feet. PW is low, less than an inch, but radar shows showers have increased overnight, mainly over water within increased low cloud cover, but also across windward slopes of Oahu and Maui.
Models show a front will approach the area over the next few days, pushing the ridge southward and causing winds across local waters to weaken. The front will stall and dissipate just north of the area Monday and Tuesday. Winds may be light enough for daytime sea breezes and nighttime land breezes to develop across some areas. Models show a slight increase in moisture as the upper ridge shifts southward. Expect an increase in windward and mauka showers, with daytime heating increasing cloud and shower coverage over interior areas during the afternoon and evening hours.
An upper trough will move over the area late Wednesday through Thursday night. Increasing moisture, along with a less stable airmass, will increase chances for showers for most of the state. Winds will remain on the lighter side during the forecast period. A drier and more stable airmass is expected to move in from the west later Friday and Saturday, with winds becoming more northerly.

Aviation

Despite the mostly dry and stable pattern in place, expect periods with MVFR CIGS over windward and mauka areas through the morning hours. Otherwise, VFR conditions are expected. Easterly trades are light enough to support the land and sea breeze regime continuing for most sites.
AIRMET SIERRA for mountain obscuration due to clouds and showers can't be ruled out by daybreak for some windward and mauka locations.

Marine

An approaching cold front passing just north of the state will weaken the ridge north of the islands through Tuesday. Another high pressure ridge will pass by far north of the Hawaii region from Tuesday into Wednesday, however trade wind speeds will remain in the light to moderate range through the period. Another cold front passes by north of the state next Wednesday, weakening the ridge and producing light and variable winds across the region on Wednesday and Thursday.
A large west-northwest swell will gradually decline into Monday and then hold through Tuesday. A High Surf Advisory (HSA) remains in effect for exposed north and west facing shores. The HSA will hold today before dropping below advisory levels later tonight into Monday. Swell directions will shift from 310 degrees today, to 320 degrees Monday, and to 330 degrees by Tuesday. The forerunners of the next large, long period, northwest swell will likely arrive late Wednesday night, quickly building to HSA levels and possibly exceeding HSW thresholds by Thursday.
Surf heights will remain small along east facing shores with background surf heights along south facing shores expected to last through the week.
Winds and seas have fallen below Small Craft Advisory thresholds and the advisory was cancelled.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST this evening for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Maui Windward West, Kona, Kohala, Kauai North, Molokai Windward, Molokai North, Molokai West, Windward Haleakala.

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Data Courtesy of NOAA.gov