Hilo

Tonight: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows 64 to 71 near the shore to 54 to 59 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Saturday: Partly sunny with showers likely in the morning, then mostly sunny with isolated showers in the afternoon. Highs 79 to 86 near the shore to 64 to 70 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Saturday Night: Mostly cloudy with scattered showers. Lows 63 to 70 near the shore to 53 to 58 at 4000 feet. North winds up to 10 mph. Chance of rain 50 percent.

Kona

Tonight: Mostly cloudy with scattered showers in the evening, then mostly clear after midnight. Lows around 74 near the shore to 50 to 55 near 5000 feet. Light winds. Chance of rain 30 percent.

Saturday: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 83 to 89 near the shore to 65 to 70 near 5000 feet. Light winds. Chance of rain 40 percent.

Saturday Night: Mostly cloudy in the evening then becoming mostly clear. Isolated showers. Lows 71 to 76 near the shore to 49 to 54 near 5000 feet. Southeast winds up to 10 mph shifting to the northeast after midnight. Chance of rain 20 percent.

Waimea

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 64 to 72 near the shore to 56 to 63 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Saturday: Mostly sunny. Breezy. Showers likely in the morning, then isolated showers in the afternoon. Highs 65 to 85. East winds 10 to 20 mph. Chance of rain 70 percent.

Saturday Night: Mostly cloudy in the evening then becoming partly cloudy. Breezy. Isolated showers. Lows 63 to 72 near the shore to 56 to 62 near 3000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Kohala

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 64 to 72 near the shore to 56 to 63 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Saturday: Mostly sunny. Breezy. Showers likely in the morning, then isolated showers in the afternoon. Highs 65 to 85. East winds 10 to 20 mph. Chance of rain 70 percent.

Saturday Night: Mostly cloudy in the evening then becoming partly cloudy. Breezy. Isolated showers. Lows 63 to 72 near the shore to 56 to 62 near 3000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

South Big Island

Tonight: Partly cloudy. Isolated showers in the evening. Lows around 75 near the shore to around 54 near 5000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Saturday: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 85 near the shore to around 67 near 5000 feet. East winds 10 to 15 mph. Chance of rain 40 percent.

Saturday Night: Mostly cloudy in the evening then clearing. Lows around 74 near the shore to around 53 near 5000 feet. East winds 10 to 15 mph.

Puna

Tonight: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows 64 to 71 near the shore to 54 to 59 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Saturday: Partly sunny with showers likely in the morning, then mostly sunny with isolated showers in the afternoon. Highs 79 to 86 near the shore to 64 to 70 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Saturday Night: Mostly cloudy with scattered showers. Lows 63 to 70 near the shore to 53 to 58 at 4000 feet. North winds up to 10 mph. Chance of rain 50 percent.

Waikoloa

Tonight: Mostly clear. Isolated showers in the evening. Lows around 75 near the shore to 52 to 57 above 4000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Saturday: Sunny. Highs 84 to 91 near the shore to 66 to 74 above 4000 feet. Northeast winds up to 10 mph.

Saturday Night: Partly cloudy. Lows around 74 near the shore to 51 to 56 above 4000 feet. East winds up to 10 mph.

Detailed Forecast

Synopsis

Gradually strengthening trade winds will become locally breezy by the weekend, delivering just a few showers, mainly to windward areas. An increase of showers are expected on Monday especially over windward Big Island, where periods of locally heavy showers will be possible.

Discussion

As the weak trough far north of the state continues to move west, high pressure will build over the area. This will allow trade winds to pick up a notch this evening into Saturday. Breezy trade wind weather is expected for the weekend with scattered showers over windward areas primarily during the night and morning hours. Leeward areas should remain mostly dry with the exception of the kona slopes of the Big Island, where scattered showers are expected each afternoon.
Starting Sunday night, a weak trough should move in from the east and will likely bring an increase of showers mainly over the Big Island. Latest GFS model is showing over 2 inches of precipitable water moving into the Big Island on Monday. Although details are uncertain, windward areas of the Big Island could see some heavy showers late Sunday night through Monday. For rest of the state, the windward side should see an increase of showers, but rainfall amounts should stay moderate. Although showers will be focused over windward and mountain areas, dewpoints should increase to the low 70s across the state. This will make temperatures feel warmer than usual on Monday.
As the plume of moisture moves away from the state Monday night, our typical moderate to locally breezy trade wind weather should return on Tuesday and hold through most of the week.

Aviation

Moderate to locally breezy trade winds with VFR conditions expected in most areas across Hawaii through the forecast period. Brief periods of MVFR conditions are likely for low ceilings and showers over localized windward and mountain locations.
Through this evening, AIRMET Sierra is posted for tempo mountain obscurations across portions of the Big Island. No other AIRMETs are currently in effect. AIRMET Sierra may need to be expanded for portions of the smaller islands overnight.

Marine

Fresh to locally strong trades continue into next week as broad high pressure develops over the NE Pacific. The Small Craft Advisory remains posted for the typical windier waters of Maui County and the Big Island through Sunday night may eventually require an extension.
Flat conditions return to N shores tonight into next week as the existing tiny N swell fades. Short period surf trends up for E facing shores due to returning trades. Nearshore PacIOOS buoys at Barber's Point off of Oahu and Kaumalapau off of Lanai indicate tiny long period S swell dominating the medium to longer period bands. This swell will generate small surf along S facing shores over the weekend with a downward trend expected early next week.

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov