Weather Forecast

Hawaii County Weather Forecast for July 18, 2021

July 18, 2021, 7:16 AM HST
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Hilo

Today: Showers likely, mainly before noon. Mostly cloudy, with a high near 82. West southwest wind 7 to 13 mph becoming east northeast in the afternoon. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Frequent showers, mainly after midnight. Low around 69. East northeast wind 5 to 9 mph becoming west after midnight. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.

Monday: Frequent showers, mainly before noon. High near 82. West wind 5 to 8 mph becoming east northeast in the afternoon. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.

Kona

Today: Scattered showers after 1pm. Partly sunny, with a high near 79. East northeast wind 5 to 8 mph becoming west in the morning. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers before 1am. Mostly cloudy, with a low around 69. Southeast wind 6 to 8 mph becoming north northeast after midnight. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

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Monday: Scattered showers after 1pm. Partly sunny, with a high near 82. West northwest wind 5 to 7 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Waimea

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Today: Scattered showers, mainly before 1pm. Partly sunny, with a high near 76. Windy, with a northeast wind 23 to 25 mph, with gusts as high as 36 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers, mainly after 7pm. Mostly cloudy, with a low around 60. Windy, with a northeast wind around 24 mph, with gusts as high as 34 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Monday: Scattered showers, mainly before 1pm. Partly sunny, with a high near 76. Windy, with a northeast wind 24 to 28 mph, with gusts as high as 40 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Kohala

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Today: Showers likely, mainly before noon. Mostly cloudy, with a high near 67. Windy, with an east wind around 29 mph, with gusts as high as 41 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Showers likely, mainly after midnight. Mostly cloudy, with a low around 58. Windy, with an east wind around 29 mph, with gusts as high as 41 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Monday: Showers likely, mainly before noon. Mostly cloudy, with a high near 69. Windy, with an east wind around 29 mph, with gusts as high as 41 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

South Big Island

Today: Mostly sunny, with a high near 83. Windy, with an east wind around 29 mph, with gusts as high as 37 mph.

Tonight: Scattered showers after midnight. Partly cloudy, with a low around 75. Windy, with an east wind 26 to 29 mph, with gusts as high as 37 mph. Chance of precipitation is 30%.

Monday: Scattered showers before noon. Mostly sunny, with a high near 86. Windy, with an east wind 24 to 29 mph, with gusts as high as 37 mph. Chance of precipitation is 30%.

Puna

Today: Showers likely, mainly before noon. Cloudy, with a high near 79. Breezy, with a northeast wind 14 to 16 mph, with gusts as high as 22 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Frequent showers, mainly after midnight. Low around 67. Breezy, with a northeast wind 11 to 15 mph becoming northwest after midnight. Winds could gust as high as 21 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.

Monday: Frequent showers, mainly before noon. High near 78. Breezy, with a northwest wind 11 to 15 mph becoming northeast in the morning. Winds could gust as high as 21 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.

Waikoloa

Today: Mostly sunny, with a high near 83. Windy, with an east northeast wind 18 to 26 mph, with gusts as high as 38 mph.

Tonight: Mostly clear, with a low around 69. Breezy, with an east northeast wind 18 to 22 mph, with gusts as high as 31 mph.

Monday: Mostly sunny, with a high near 84. Windy, with an east northeast wind 20 to 25 mph decreasing to 9 to 14 mph in the afternoon. Winds could gust as high as 36 mph.

Detailed Forecast

Synopsis

The dry and breezy summertime trade wind pattern will persist through much of the week. With the exception of the Kona slopes, the drought conditions will continue over leeward areas with limited rainfall chances in the forecast. Any showers that do develop will be brief and favor windward and mauka locations, with the best chances being overnight through the early morning hours as pockets of moisture move through.

Discussion

Guidance remains in good agreement and depicts the dry and stable trade wind conditions prevailing through much of the week as high pressure strengthens to the north. Easterly trade winds will respond and become strong later today through the first half of the week. Winds may near the advisory criteria in the typically windier areas of Maui County and the Big Island by Monday afternoon. Although limited rainfall is anticipated over our dry leeward areas where drought conditions prevail, the strong trades may offer some potential for a few brief showers reaching these parched soils. The best rainfall chances will remain over windward/mauka areas overnight through the early morning hours. For the extended, it remains too early to determine whether or not any remnant moisture from the tropical systems currently (Felicia/Guillermo) in the eastern Pacific will move into the area later this week into next weekend.

Aviation

A high pressure system far north of the islands will keep moderate to breezy trade winds in the forecast today. An upper level disturbance will produce passing showers, favoring windward and mountain areas in the overnight to early morning hours.
AIRMET Sierra remains in effect for Mountain Obscuration over north and east sections of Oahu and Kauai due to low cloud ceilings and showers.
AIRMET Tango remains in effect for Moderate Turbulence over and south through west of island mountains due to the stronger trade winds. This AIRMET will remain in effect through Monday.

Marine

Surface high pressure located far north of the area will produce strong trade winds and elevated, rough seas across the state through Tuesday. As a result, a Small Craft Advisory (SCA) has been issued for most waters surrounding the islands. Based on the latest forecast trends, the SCA may be required for only the typically windier waters adjacent to the islands of Maui County and the Big Island from Wednesday through Thursday.
The current south swell will likely hold into this evening, then will gradually trend lower from late tonight through Monday. This is expected to maintain surf heights near or above the summer average along south facing shores into Monday. This south swell will continue to subside Tuesday and Wednesday, returning surf along south facing shores to below normal summertime heights by mid-week. The strengthening trade winds will result in slightly elevated, rough surf along east facing shores through the first half of the new week. Besides some localized wrap of trade wind swell, surf along most north facing shores will remain essentially flat through mid-week.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Monday for Kauai Northwest Waters, Kauai Leeward Waters, Kauai Channel, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, 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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