Weather Forecast

Hawaii County Weather Forecast for September 04, 2021

September 4, 2021, 7:16 AM HST
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Hilo

Today: Mostly cloudy. Breezy. Showers likely in the morning, then scattered showers in the afternoon. Highs 82 to 88 near the shore to around 70 at 4000 feet. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Showers likely in the evening, then occasional showers after midnight. Lows 66 to 73 near the shore to around 54 at 4000 feet. North winds around 10 mph. Chance of rain 90 percent.

Sunday: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 81 to 87 near the shore to around 70 at 4000 feet. East winds around 10 mph. Chance of rain 70 percent.

Kona

Today: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 82 to 87 near the shore to 67 to 72 near 5000 feet. West winds around 10 mph in the morning becoming light. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then mostly clear with isolated showers after midnight. Lows 68 to 73 near the shore to around 54 near 5000 feet. Light winds becoming northwest around 10 mph after midnight. Chance of rain 50 percent.

ARTICLE CONTINUES BELOW AD

Sunday: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 81 to 86 near the shore to 67 to 72 near 5000 feet. Light winds. Chance of rain 50 percent.

Waimea

ARTICLE CONTINUES BELOW AD

Today: Breezy. Partly sunny with scattered showers. Highs around 83 near the shore to 75 to 80 near 3000 feet. East winds 15 to 25 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 68 near the shore to 56 to 62 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs around 82 near the shore to 74 to 80 near 3000 feet. East winds around 10 mph. Chance of rain 50 percent.

Kohala

ARTICLE CONTINUES BELOW AD

Today: Breezy. Partly sunny with scattered showers. Highs around 83 near the shore to 75 to 80 near 3000 feet. East winds 15 to 25 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 68 near the shore to 56 to 62 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs around 82 near the shore to 74 to 80 near 3000 feet. East winds around 10 mph. Chance of rain 50 percent.

South Big Island

Today: Breezy. Sunny in the morning, then cloudy with isolated showers in the afternoon. Highs around 84 near the shore to around 74 near 5000 feet. East winds 10 to 25 mph decreasing to up to 25 mph in the afternoon. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers in the evening, then mostly clear after midnight. Lows around 69 near the shore to around 53 near 5000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Sunday: Sunny in the morning, then cloudy with isolated showers in the afternoon. Highs around 84 near the shore to around 74 near 5000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Puna

Today: Mostly cloudy. Breezy. Showers likely in the morning, then scattered showers in the afternoon. Highs 82 to 88 near the shore to around 70 at 4000 feet. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Showers likely in the evening, then occasional showers after midnight. Lows 66 to 73 near the shore to around 54 at 4000 feet. North winds around 10 mph. Chance of rain 90 percent.

Sunday: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 81 to 87 near the shore to around 70 at 4000 feet. East winds around 10 mph. Chance of rain 70 percent.

Waikoloa

Today: Mostly sunny. Breezy. Highs 83 to 88 near the shore to 68 to 75 above 4000 feet. Northeast winds 10 to 25 mph decreasing to up to 25 mph in the afternoon.

Tonight: Mostly clear. Lows around 72 near the shore to 51 to 58 above 4000 feet. Southeast winds up to 10 mph.

Sunday: Mostly sunny. Highs 82 to 87 near the shore to 68 to 75 above 4000 feet. Light winds.

Detailed Forecast

Synopsis

Trade winds will decrease slightly today, then diminish further on Sunday, remaining light to moderate for most of next week. Clouds and showers will favor windward areas. Leeward areas may see increased afternoon clouds and showers after trade flow weakens.

Discussion

A high remains north of the islands, driving strong trades winds across the area this morning. There is little or no change in forecast philosophy from last evening, other than keeping a Small Craft Advisory up through this afternoon for all coastal waters due to continued strong winds seen in an overnight ASCAT pass. Satellite loop shows an area of low clouds affecting windward and southeast portions of the Big Island as well as windward portions of Maui, but not a lot of clouds immediately upstream of the remaining islands. Overnight soundings show PW values have recovered a bit from yesterday afternoon, ranging now from 1.30 to 1.35 inches. Scarce cloud cover and short linger times due to strong winds will keep rainfall light through the weekend.
As surface winds pick up after sunrise today, they will not be quite as strong as they were yesterday. Models show winds will continue to trend down Sunday into Monday as a low and front pass far north of the area, weakening the ridge north of the region. This should return us to a light to moderate trade wind pattern for most of next week. A closed upper low is expected to form northeast of the islands Sunday night and a surface trough is expected to form beneath it. This combination will contribute to weaker winds at that time. Lighter trades will deliver a few windward showers during nights and mornings, with afternoon sea breezes potentially driving the formation of clouds and a few showers over leeward areas.

Aviation

Robust high pressure far north of the area is sustaining breezy to locally strong trade winds across the isles, with a modest easing of the trades anticipated today. Most locales will remain VFR through tonight, with brief MVFR possible in lower clouds and showers mainly in windward and mauka sections from time to time.
An AIRMET for low level turbulence remains in effect to the lee of the mountains across the island chain, with it likely to be extended through this afternoon.

Marine

High pressure north of the state will continue to produce breezy to locally windy trade winds for most areas through today. As a result, a Small Craft Advisory (SCA) has been extended for all Hawaiian Coastal Waters through this afternoon. The high will begin to weaken later today through early next week. In response, trade winds will begin to lower in strength later today, and become light to locally moderate Sunday through Wednesday. The SCA will likely remain posted for the typically windy waters around Maui County and the Big Island through tonight but may be lowered over the remaining Hawaiian Coastal Waters later today.
There will be a series of small south swells through the rest of the weekend and on through the middle of next week with a slightly larger south swell possible later in the week. Trade winds in the South Pacific will continue to produce a small, short period southeast swell throughout the forecast period. Elevated surf along east facing shores will gradually lower later today as trade winds speeds ease through early next week. No other significant swells are expected.

Fire weather

Strong trade winds, combined with the Keetch- Byram Drought Index (KBDI) over 600 and low relative humidity, support continuation of the Red Flag Warning (RFW) for leeward areas of nearly all islands. Winds are expected to ease a bit, but will be strong enough to warrant continuing the RFW through this afternoon. Expect lower relative humidities again this afternoon during the heat of the day and expect winds to pick up again after sunrise, peaking during the afternoon hours.

HFO Watches/Warnings/Advisories

Red Flag Warning until 6 PM HST this evening for Kauai Leeward, Oahu South Shore, Waianae Coast, Oahu North Shore, Olomana, Central Oahu, Waianae Mountains, Molokai Leeward, Maui Leeward West, Maui Central Valley, Leeward Haleakala, Kona, Kohala, Big Island Interior.
Small Craft Advisory until 6 AM HST Sunday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.
Small Craft Advisory until 6 PM HST this evening for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Big Island Windward Waters.

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Data Courtesy of NOAA.gov

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