Weather Forecast

Hawaii County Weather Forecast for October 05, 2021

October 5, 2021, 7:15 AM HST
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Photo Credit: James Grenz

Hilo

Today: Partly sunny with scattered showers. Highs 78 to 84 near the shore to 64 to 70 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Showers likely in the evening, then occasional showers after midnight. Lows around 69 near the shore to around 55 at 4000 feet. Northeast winds 10 to 15 mph shifting to the northwest after midnight. Chance of rain 80 percent.

Wednesday: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 81 to 87 near the shore to 68 to 73 at 4000 feet. Northwest winds 10 to 15 mph shifting to the northeast in the afternoon. Chance of rain 70 percent.

Kona

Today: Mostly cloudy. Haze through the day. Scattered showers in the afternoon. Highs 83 to 88 near the shore to around 67 near 5000 feet. West winds around 10 mph. Chance of rain 30 percent.

Tonight: Mostly cloudy with isolated showers. Haze. Lows 71 to 76 near the shore to around 55 near 5000 feet. Light winds. Chance of rain 20 percent.

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Wednesday: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Haze through the day. Highs around 86 near the shore to around 73 near 5000 feet. Light winds. Chance of rain 40 percent.

Waimea

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Today: Breezy. Partly sunny with scattered showers. Highs 64 to 84. East winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 68 near the shore to 56 to 63 near 3000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Wednesday: Breezy. Partly sunny with scattered showers. Highs around 83 near the shore to 73 to 79 near 3000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Kohala

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Today: Breezy. Partly sunny with scattered showers. Highs 64 to 84. East winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 68 near the shore to 56 to 63 near 3000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Wednesday: Breezy. Partly sunny with scattered showers. Highs around 83 near the shore to 73 to 79 near 3000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

South Big Island

Today: Breezy. Partly sunny in the morning, then cloudy with isolated showers in the afternoon. Haze through the day. Highs around 84 near the shore to around 66 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Breezy. Isolated showers in the evening. Haze through the night. Lows around 71 near the shore to around 54 near 5000 feet. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Wednesday: Breezy. Sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Haze through the day. Highs around 85 near the shore to around 74 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Puna

Today: Partly sunny with scattered showers. Highs 78 to 84 near the shore to 64 to 70 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Showers likely in the evening, then occasional showers after midnight. Lows around 69 near the shore to around 55 at 4000 feet. Northeast winds 10 to 15 mph shifting to the northwest after midnight. Chance of rain 80 percent.

Wednesday: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 81 to 87 near the shore to 68 to 73 at 4000 feet. Northwest winds 10 to 15 mph shifting to the northeast in the afternoon. Chance of rain 70 percent.

Waikoloa

Today: Partly sunny. Breezy. Highs 83 to 88 near the shore to 66 to 72 above 4000 feet. Northeast winds 10 to 20 mph.

Tonight: Breezy. Partly cloudy with isolated showers in the evening, then mostly cloudy after midnight. Lows around 74 near the shore to 51 to 58 above 4000 feet. Northeast winds 10 to 20 mph shifting to the southeast 10 to 15 mph after midnight. Chance of rain 20 percent.

Wednesday: Sunny and breezy. Highs around 85 near the shore to 69 to 75 above 4000 feet. Southeast winds 10 to 25 mph shifting to the northeast in the afternoon.

Detailed Forecast

Synopsis

Moderate to locally breezy trade winds will strengthen Wednesday through Friday, with windy conditions anticipated over the weekend. Clouds and showers will tend to focus over windward and mauka areas, but will occasionally blow leeward, especially with the stronger winds.

Discussion

Trade winds will prevail through the forecast period, supported by surface high pressure to the distant N and NE. Moderate to locally breezy trade winds are expected into Wednesday, with a steady strengthening of the trade winds expected from Wednesday into Friday as high pressure consolidates and moves S toward the islands. Some lowering of surface pressures to the S of the islands will add to the gradient over the weekend, and windy conditions appear likely at that time. A Wind Advisory will likely be required for at least portions of the area. Trade wind speeds may remain elevated into early next week.
An E-W oriented trough aloft several hundred miles N of the islands is transporting some high clouds over the Big Island and adjacent waters, and is still supporting some instability over the Kauai end of the chain. However, a lack of significant moisture will limit shower coverage and intensity. The general expectation is therefore for breezy trades to support a typical trade wind weather pattern into the weekend as the trough aloft gradually weakens. Although showers will tend to be focused over windward and mauka areas during this time, the strengthening trades will tend to carry showers leeward with greater efficiency, particularly at night and early morning.
Long range guidance indicates a surge in moisture approaching the islands from the SE in about a week or so. Confidence is low in this outcome, but it bears watching.

Aviation

Moderate to locally strong trades will continue through tonight, with high pressure centered well north of the islands. Beginning Wednesday, high pressure will be forced southward, increasing the local pressure gradient and causing trades to ramp up quickly. AIRMET Tango for low-level turbulence in the lee of the mountains remains in effect and will likely remain so for the next several days.
VFR conditions will prevail across the state through the next 24 hours, with brief MVFR cigs/vis possible across windward sections from areas of moisture embedded in the low-level trade wind flow.

Marine

High pressure north of the area will continue to produce moderate to breezy trade winds. A Small Craft Advisory (SCA) is currently posted for the typically windy waters around Maui County and the Big Island. A stronger high will build north of the area beginning tonight into Wednesday. The SCA will likely be expanded across most other coastal waters by later in the week as trades increase into the breezy to strong range.
A small, long period west northwest swell will continue to fill in, peak later today through early Wednesday, then lower gradually through the remainder of the week and on through the weekend. A series of small, mainly background south swells can be expected through Thursday. A larger long period south swell is expected to fill in by Friday, peak Saturday, then lower slowly through Sunday. Easterly trade winds will continue to produce short period choppy surf along east facing shores through Wednesday. With the expected increase in trade winds over and upwind of the islands beginning Wednesday, surf heights are expected to increase later in the week and on into the weekend.

Fire weather

With above-average KBDI values still well above 600, the strengthening winds over the next couple of days could result in Red Flag Warning conditions, depending if RH values get sufficiently low. Forecast confidence is not high enough to issue a Fire Weather Watch at this juncture.

HFO Watches/Warnings/Advisories

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

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