Hilo

Tonight: Partly cloudy with scattered showers. Lows 61 to 69 near the shore to 51 to 58 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 50 percent.

Monday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 80 near the shore to around 67 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy with numerous showers. Lows 60 to 69 near the shore to 51 to 58 at 4000 feet. North winds up to 15 mph. Chance of rain 70 percent.

Kona

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy after midnight. Haze through the night. Lows 69 to 74 near the shore to 49 to 54 near 5000 feet. Light winds. Chance of rain 40 percent.

Monday: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Haze through the day. Highs 82 to 87 near the shore to around 68 near 5000 feet. West winds up to 10 mph. Chance of rain 40 percent.

Monday Night: Partly cloudy. Haze in the evening. Lows 69 to 74 near the shore to around 51 near 5000 feet. Light winds.

Waimea

Tonight: Breezy. Partly cloudy with isolated showers. Lows 62 to 71 near the shore to 54 to 61 near 3000 feet. East winds up to 25 mph. Chance of rain 20 percent.

Monday: Breezy. Mostly sunny with isolated showers. Highs around 80 near the shore to 69 to 78 near 3000 feet. East winds up to 25 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 20 percent.

Monday Night: Breezy. Mostly cloudy with scattered showers. Lows 61 to 70 near the shore to 54 to 62 near 3000 feet. East winds 10 to 25 mph with gusts to 45 mph. Chance of rain 50 percent.

Kohala

Tonight: Breezy. Partly cloudy with isolated showers. Lows 62 to 71 near the shore to 54 to 61 near 3000 feet. East winds up to 25 mph. Chance of rain 20 percent.

Monday: Breezy. Mostly sunny with isolated showers. Highs around 80 near the shore to 69 to 78 near 3000 feet. East winds up to 25 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 20 percent.

Monday Night: Breezy. Mostly cloudy with scattered showers. Lows 61 to 70 near the shore to 54 to 62 near 3000 feet. East winds 10 to 25 mph with gusts to 45 mph. Chance of rain 50 percent.

South Big Island

Tonight: Mostly clear. Breezy. Haze through the night. Lows around 74 near the shore to around 54 near 5000 feet. Northeast winds up to 20 mph increasing to 10 to 20 mph after midnight.

Monday: Mostly sunny. Breezy. Haze through the day. Isolated showers in the afternoon. Highs around 85 near the shore to around 68 near 5000 feet. East winds up to 25 mph. Chance of rain 20 percent.

Monday Night: Partly cloudy. Breezy. Haze through the night. Lows around 74 near the shore to around 54 near 5000 feet. Northeast winds up to 20 mph increasing to 10 to 20 mph after midnight.

Puna

Tonight: Partly cloudy with scattered showers. Lows 61 to 69 near the shore to 51 to 58 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 50 percent.

Monday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 80 near the shore to around 67 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy with numerous showers. Lows 60 to 69 near the shore to 51 to 58 at 4000 feet. North winds up to 15 mph. Chance of rain 70 percent.

Waikoloa

Tonight: Partly cloudy. Breezy. Haze in the evening. Lows 69 to 74 near the shore to 50 to 55 above 4000 feet. Southeast winds up to 20 mph.

Monday: Mostly sunny. Haze through the day. Isolated showers in the afternoon. Highs 82 to 87 near the shore to 65 to 73 above 4000 feet. Southeast winds up to 15 mph shifting to the northwest in the afternoon. Chance of rain 20 percent.

Monday Night: Partly cloudy. Breezy. Lows 69 to 74 near the shore to 50 to 55 above 4000 feet. Southeast winds up to 25 mph with gusts to 45 mph.

Detailed Forecast

Synopsis

High pressure will strengthen trade wind speeds Monday into Tuesday, then taper off Wednesday through the end of the week. A remnant front will increase showers Monday into Tuesday focusing windward and occasionally reaching leeward sides. Drier and more stable trade winds expected from Wednesday to Friday.

Discussion

A strong high far north northwest of the area will slowly dig southeastward and tightening the gradient between a stationary and persistent low pressure system west of the main Hawaiian Islands. As a result, trade winds will be increasing through Monday and maintaining Tuesday before weakening as the high is squeezed between two lows.
Moisture from a remnant front will make its way southward as the ridge builds, bringing clouds and showers to the area Monday and Tuesday. The band will track north to south, but easterly trades will focus showers windward, but occasionally reaching leeward sides as well.
Lighter and drier trades are expected Wednesday as a more stable airmass propagates across the islands, persisting through the reminder of the week. Model guidance remains in reasonable agreement, proposing another frontal boundary just west of the islands toward the end of the outlook period. Further analysis will be necessary to determine the timing and impacts of this front, as confidence remains too low for now.

Aviation

The trade winds have gradually returned today across the state, with some locations in Maui County experiencing gusty winds. Expect the winds to continue strengthening tomorrow, which may warrant AIRMET Tango to be issued for low level turbulence downwind of terrain. Showers embedded within the trade winds may bring brief MVFR conditions to windward and mauka areas. Otherwise, VFR will prevail.
There are no AIRMETs currently in effect.

Marine

Building high pressure will favor fresh to locally strong trades through the week, peaking at near-gales on a localized basis during Tuesday. Winds veer to SE this weekend in advance of low pressure. The Small Craft Advisory for winds remains in effect.
Modeling indicates remnants of the existing NNW is on its way out, confirmed by nearshore PacIOOS Buoys for Waimea Bay, Makapu'u Point, and Pauwela which are dominated entirely by N (350-010) swell through the medium and long period bands today. The nearshore observations indicate this swell has held steady for the balance of today, though indications from offshore NDBC 51000 are that it will resume trending downward tonight into tomorrow. Forerunners associated with a building moderate N to NNE (010-020) swell are forecast to arrive by late Wednesday bringing moderate surf to favored exposures Thursday into Friday night. A Marine Weather Statement (MWS) is in effect for moderate harbor surges associated with the current N swell, and another MWS may be needed for the next swell in the sequence Wednesday night through Friday.
Returning trades produce building surf along E facing shores beginning today and peaking with building trades on Tuesday. Surf then diminishes during the second half of the week as trades weaken and veer to SE. Surf along S shores remains tiny with fleeting background S to SSW energy through the week.

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov