Hawaii County Weather Forecast for September 23, 2021
Hilo
Today: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 80 to 86 near the shore to 68 to 73 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.
Tonight: Mostly cloudy with showers likely. Lows around 68 near the shore to around 54 at 4000 feet. Northwest winds up to 15 mph. Chance of rain 70 percent.
Friday: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 80 to 86 near the shore to 68 to 73 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.
Kona
Today: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 86 near the shore to around 73 near 5000 feet. Northwest winds up to 10 mph shifting to the southwest in the afternoon. Chance of rain 50 percent.
Tonight: Partly cloudy. Isolated showers in the evening. Lows 68 to 74 near the shore to around 54 near 5000 feet. Light winds. Chance of rain 20 percent.
Friday: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 86 near the shore to around 73 near 5000 feet. Light winds. Chance of rain 50 percent.
Waimea
Today: Mostly cloudy. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 82 near the shore to 73 to 80 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.
Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 67 near the shore to 54 to 61 near 3000 feet. East winds 10 to 20 mph decreasing to up to 20 mph after midnight. Chance of rain 50 percent.
Friday: Mostly cloudy. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 82 near the shore to 73 to 80 near 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.
Kohala
Today: Mostly cloudy. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 82 near the shore to 73 to 80 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.
Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 67 near the shore to 54 to 61 near 3000 feet. East winds 10 to 20 mph decreasing to up to 20 mph after midnight. Chance of rain 50 percent.
Friday: Mostly cloudy. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 82 near the shore to 73 to 80 near 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.
South Big Island
Today: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 85 near the shore to around 74 near 5000 feet. East winds up to 15 mph. Chance of rain 20 percent.
Tonight: Partly cloudy. Lows around 68 near the shore to around 53 near 5000 feet. Northeast winds up to 15 mph.
Friday: Breezy. Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 85 near the shore to around 74 near 5000 feet. East winds up to 25 mph. Chance of rain 20 percent.
Puna
Today: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 80 to 86 near the shore to 68 to 73 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.
Tonight: Mostly cloudy with showers likely. Lows around 68 near the shore to around 54 at 4000 feet. Northwest winds up to 15 mph. Chance of rain 70 percent.
Friday: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 80 to 86 near the shore to 68 to 73 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.
Waikoloa
Today: Mostly sunny in the morning then becoming partly sunny. Breezy. Highs around 85 near the shore to 69 to 75 above 4000 feet. Northeast winds up to 20 mph.
Tonight: Partly cloudy. Breezy. Lows 69 to 74 near the shore to 50 to 57 above 4000 feet. Southeast winds up to 20 mph.
Friday: Mostly sunny in the morning then becoming partly sunny. Breezy. Highs around 85 near the shore to 69 to 75 above 4000 feet. Northeast winds up to 20 mph.
Detailed Forecast
Synopsis
Breezy trade winds will continue through the weekend, with clouds and showers favoring windward and mauka locations overnight through the morning periods. Very little moisture making it into leeward areas will translate to the drought conditions prevailing. A slight increase in windward shower coverage can’t be ruled out late Saturday night through the second half of the weekend as a weak trough passes to the south. A return of drier trade wind conditions is expected early next week.
Discussion
Guidance remains in good agreement heading into the weekend and depicts rising upper heights as the upper ridge noses westward over the region and an upper low to the west moves out. Plenty of middle- to upper-level dry air combined with a strong subsidence inversion and surface ridge anchored north of the area will support the stable trade wind pattern holding through the first half of the weekend. The northern periphery of an area of enhanced low-level moisture associated with a weak trough passing to the south Sunday through Monday may translate to better windward and mauka showers – best chance over the Big Island. A return of drier trade wind conditions is shown early next week as the surface trough continues westward and diminishes.
Aviation
With a nearly stationary high pressure center remaining far north of the area, trade winds will persist in the moderate to locally breezy range through today and beyond. VFR will prevail over most areas most of the time, but lower cloudiness and showers moving along with the trades will bring MVFR conditions to mainly windward and mauka sections from time to time.
An AIRMET remains in effect for low level turbulence to the lee of the mountains statewide. However, this will likely be cancelled with the next issuance.
Marine
The Small Craft Advisory (SCA) for traditionally windier waters around Maui and the Big Island has been cancelled. Seas will near the SCA level threshold again Friday due to a combination of a north-northwest swell and trade wind waves.
A northwest swell will gradually ease through today. A larger north-northwest swell should begin to fill in tonight and peak Friday, with surf likely below advisory levels along exposed north and west facing shores of the smaller islands. This swell will slowly fade into the weekend. Surf along south facing shores will remain elevated through the second half of the week as a long-period south swell moves through. This should peak today before fading into the weekend. Surf along east facing shores will remain small and choppy due to the fresh/strong trades locally and just upstream of the state.
HFO Watches/Warnings/Advisories
None.
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Data Courtesy of NOAA.gov