Hilo

Tonight: Mostly cloudy with scattered showers. Lows 67 to 75 near the shore to around 61 at 4000 feet. North winds up to 15 mph. Chance of rain 50 percent.

Monday: Mostly cloudy. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 81 to 86 near the shore to 68 to 74 at 4000 feet. North winds up to 20 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Locally heavy rainfall possible in the evening. Lows 69 to 75 near the shore to around 63 at 4000 feet. North winds up to 10 mph. Gusts up to 30 mph. Chance of rain 70 percent.

Kona

Tonight: Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Lows 71 to 77 near the shore to around 59 near 5000 feet. Light winds. Chance of rain 20 percent.

Monday: Mostly sunny. Highs 86 to 91 near the shore to around 73 near 5000 feet. Southwest winds up to 10 mph.

Monday Night: Partly cloudy. Lows 71 to 78 near the shore to around 59 near 5000 feet. Light winds.

Waimea

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then isolated showers after midnight. Lows 67 to 75 near the shore to 62 to 69 near 3000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Monday: Mostly cloudy. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 83 near the shore to 72 to 82 near 3000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows 69 to 76 near the shore to 64 to 70 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Kohala

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then isolated showers after midnight. Lows 67 to 75 near the shore to 62 to 69 near 3000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Monday: Mostly cloudy. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 83 near the shore to 72 to 82 near 3000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows 69 to 76 near the shore to 64 to 70 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

South Big Island

Tonight: Breezy. Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Lows around 78 near the shore to around 62 near 5000 feet. Northeast winds up to 20 mph. Chance of rain 20 percent.

Monday: Mostly sunny. Highs around 88 near the shore to around 73 near 5000 feet. East winds up to 15 mph.

Monday Night: Partly cloudy in the evening then becoming mostly cloudy. Lows around 79 near the shore to around 62 near 5000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph after midnight.

Puna

Tonight: Mostly cloudy with scattered showers. Lows 67 to 75 near the shore to around 61 at 4000 feet. North winds up to 15 mph. Chance of rain 50 percent.

Monday: Mostly cloudy. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 81 to 86 near the shore to 68 to 74 at 4000 feet. North winds up to 20 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Locally heavy rainfall possible in the evening. Lows 69 to 75 near the shore to around 63 at 4000 feet. North winds up to 10 mph. Gusts up to 30 mph. Chance of rain 70 percent.

Waikoloa

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Breezy. Lows 73 to 78 near the shore to 57 to 62 above 4000 feet. East winds up to 25 mph.

Monday: Mostly sunny. Breezy. Highs 86 to 93 near the shore to 72 to 77 above 4000 feet. Northeast winds up to 25 mph.

Monday Night: Partly cloudy in the evening then becoming mostly cloudy. Breezy. Lows around 76 near the shore to around 61 above 4000 feet. East winds up to 20 mph decreasing to up to 10 mph after midnight.

Detailed Forecast

Synopsis

Breezy trades weaken slightly during midweek then restrengthen by late in the week. Potential tropical development threatens to bring heavy rainfall to eastern portions of the state during the latter half of the week, though uncertainty remains higher than usual at this time.

Short term update

Moderately stable breezy trades prevail at press with limited showers observed on area radar composite. SW flow around the periphery of a trough positioned northwest of the islands is drawing high clouds northward over area skies, but it is not a particularly meaningful feature otherwise. Dry mid-level air encroaching from the NE will further strengthen stability over the western half of the state on Monday while deeper moisture entrained in the trades reaches the Big Island resulting in a greater coverage of windward showers there.

Aviation

Issued at 312 PM HST Sun Sep 20 2026 Breezy trades will continue into Monday. Isolated showers and brief MVFR conditions are possible mainly over windward and mountain areas. Shower activity may increase by Monday night, especially over windward areas of Big Island.
AIRMET Tango remains in effect for moderate low-level turbulence downwind of island terrain due to the breezy trades.

Marine

Issued at 312 PM HST Sun Sep 20 2026 The gradient between weak high pressure north of the islands and pressure falls south of the islands will maintain fresh to locally strong trade winds across the region through at least Monday night. Therefore, the Small Craft Advisory has been extended through Monday night for the typical windy channels and waters of Maui County and the Big Island. After a slight reduction in trade wind speeds heading into mid week, they will restrengthen during the latter half of the week as a trough or potential weak tropical disturbance moves south of the islands. Shower coverage will also increase, along with the potential for isolated thunderstorms, particularly across the eastern waters.
Surf along south facing shores will remain above average over the next couple of days as a long period SSW swell holds relatively steady. This swell will then gradually fade heading into mid week. A slightly smaller, long-period south-southwesterly swell will fill in late this week into next weekend generated by a series of lows near New Zealand. West facing shores will experience a bit of the southerly wrap through most of the week.
Breezy trade winds will maintain moderate surf along east facing shores for the next several days. Surf along north facing shores will remain flat to tiny through Monday, but will see a slight bump Tuesday into Wednesday as a small, medium-period northwest swell fills in from an Aleutian low. Then a small, long-period west-northwest swell expected to be generated by Tropical Storm Dujuan as it curves northeast near Japan and potentially strengthens into a hurricane will build locally Friday into next weekend, increasing surf along north and west facing shores.

Fire weather

Issued at 312 PM HST Sun Sep 20 2026 Fire weather risk remains low. Locally breezy trade winds are expected through at least Monday. However, dewpoints in the low 70s will keep relative humidity in check. Inversion heights are around 6000 feet statewide.

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov