Hilo, Hawaii Weather

Overnight

65° F
Scattered Rain Showers
Wind 5 mph SSE

Thursday

82° F
Scattered Rain Showers
Wind 5 to 8 mph E

Thursday Night

65° F
Scattered Rain Showers
Wind 5 mph ESE

Friday

82° F
Scattered Rain Showers
Wind 3 to 8 mph ENE

Friday Night

64° F
Occasional Rain Showers
Wind 3 mph NE

Saturday

83° F
Rain Showers Likely
Wind 3 to 8 mph ENE

Saturday Night

65° F
Occasional Rain Showers
Wind 5 mph ENE

Sunday

83° F
Rain Showers Likely
Wind 5 to 8 mph ENE

Sunday Night

65° F
Rain Showers Likely
Wind 5 mph ESE

Monday

83° F
Rain Showers Likely
Wind 3 to 8 mph ESE

Monday Night

65° F
Rain Showers Likely
Wind 7 mph SE

Tuesday

83° F
Rain Showers Likely
Wind 8 mph SE

Tuesday Night

65° F
Rain Showers Likely
Wind 6 mph SE

Wednesday

83° F
Rain Showers Likely
Wind 6 to 9 mph SE
LOADING RADAR

Hawaii County Weather Forecast for April 21, 2021

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Photo Credit: James Grenz

Hilo

Today: Scattered showers, mainly before noon. Partly sunny, with a high near 82. West southwest wind 6 to 11 mph becoming east in the morning. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 63. South wind around 5 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Thursday: Scattered showers, mainly before noon. Partly sunny, with a high near 82. East northeast wind 5 to 8 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Kona

Today: Isolated showers after noon. Partly sunny, with a high near 84. Northeast wind 6 to 10 mph becoming west in the morning. Chance of precipitation is 20%.

Tonight: Isolated showers. Mostly cloudy, with a low around 63. West northwest wind around 5 mph becoming south in the evening. Chance of precipitation is 20%.

Thursday: Isolated showers after noon. Partly sunny, with a high near 83. West wind around 5 mph becoming north in the afternoon. Chance of precipitation is 20%.

Waimea

Today: Scattered showers, mainly after noon. Partly sunny, with a high near 75. Southeast wind 6 to 9 mph becoming north northwest in the morning. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 52. East wind 5 to 11 mph. Chance of precipitation is 30%. New precipitation amounts between a tenth and quarter of an inch possible.

Thursday: Scattered showers, mainly before noon. Mostly sunny, with a high near 74. East northeast wind 11 to 13 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Kohala

Today: Scattered showers. Partly sunny, with a high near 68. East wind around 9 mph becoming north northwest in the morning. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Partly cloudy, with a low around 44. Breezy, with an east wind 9 to 15 mph, with gusts as high as 21 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Thursday: Scattered showers, mainly before noon. Partly sunny, with a high near 67. Breezy, with an east northeast wind 15 to 17 mph, with gusts as high as 24 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

South Big Island

Today: Isolated showers after noon. Partly sunny, with a high near 84. Northeast wind around 11 mph becoming southeast in the morning. Chance of precipitation is 20%.

Tonight: Isolated showers. Partly cloudy, with a low around 69. Breezy, with an east northeast wind 14 to 18 mph, with gusts as high as 23 mph. Chance of precipitation is 20%.

Thursday: Mostly sunny, with a high near 83. Windy, with an east wind 18 to 24 mph, with gusts as high as 31 mph.

Puna

Today: Scattered showers, mainly before noon. Partly sunny, with a high near 80. West southwest wind 6 to 11 mph becoming east in the morning. Chance of precipitation is 50%. New precipitation amounts between a tenth and quarter of an inch possible.

Tonight: Showers likely, mainly after midnight. Mostly cloudy, with a low around 61. Northeast wind 5 to 8 mph. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.

Thursday: Scattered showers. Partly sunny, with a high near 79. Northeast wind 8 to 14 mph, with gusts as high as 18 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Waikoloa

Today: Scattered showers after noon. Partly sunny, with a high near 81. East wind 6 to 10 mph becoming west northwest in the morning. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Isolated showers before midnight. Partly cloudy, with a low around 62. East wind around 5 mph. Chance of precipitation is 20%.

Thursday: Mostly sunny, with a high near 80. North wind around 6 mph.

Detailed Forecast

Synopsis

High clouds will gradually decrease today. Leeward sea breezes will support inland clouds and a few showers this afternoon. Breezy trades and more typical trade wind weather will return by the end of the week.

Discussion

Overcast mid and high clouds are thinning and slowly pushing southward as an upper wave shifts east of the area. Showers remain confined to the adjacent waters of Kauai and southeast sections of Big Island. Light winds and land breezes will maintain dry conditions over the smaller islands through early this morning. Mid-level subsidence associated with a building ridge from the west will bring an increase in stability today. However, the existing ribbon of deep moisture over the area will still hold in place through at least the lowest 10kft. As a result, afternoon leeward sea breezes should have an easy time causing afternoon cloud build-ups and a even few showers over inland areas. The same could be said for Thursday, although the gradual increase in trades reduces confidence in sea breeze development. So, showers may instead manifest in more typical trade wind fashion by Thursday afternoon, especially for Oahu through Big Island.
Locally breezy trades will return by week’s end as high pressure establishes over the north-central pacific. There is strong model consensus that weak shortwave energy currently near 170E/35N will shear toward the islands along the eastern periphery of the building ridge, eventually cutting off near or directly over the area this weekend. The resulting reduction in stability will support a wetter trade wind pattern for the weekend. Low confidence with respect to the to the evolution of this closed low results in higher than normal forecast uncertainty by early next week.

Aviation

A trough northwest of the islands continues to spread layered clouds across the whole of the state. As of 2am HST, radar indicated only isolated light showers within the layered clouds. These conditions are expected to persist throughout the day today. Mostly clear skies developing across the smaller islands late this evening.
On the Big Island, weak southeasterly flow will steer bands of low topped clouds and isolated showers towards east facing slopes and coasts this morning. In the afternoon and early evening hours, light sea breezes will focus shower activity over the island’s interior.
SIGMET Xray is in effect for severe turbulence above FL320 associated with a digging upper level trough. The band of moderate to severe upper level turbulence currently affects all the smaller islands and will spread across the Big Island within the next few hours. Conditions should improve from the northwest later this morning.

Marine

A trough northwest of Kauai will gradually dissipate through Friday. In doing so, light trade winds are expected to spread westward from Maui and the Big Island today. A surface high is forecast to pass north of the islands Thursday through Friday, resulting in a boost in the trade winds with speeds reaching locally strong for especially the sensitive nearshore areas of Maui County and waters south of the Big Island. This breezy trades will persist through Sunday followed by a drop off Sunday night into Monday. A Small Craft Advisory for those nearshore waters will be hoisted as early as tonight.
A small to moderate northwest swell arriving today will lead to a bump up to the north and west facing shores. This swell will max out Thursday followed by a gradual decline through Friday. A small to moderate long period west-northwest swell is slated to arrive next week Monday night and peak Tuesday, followed by a slow decline. A continuous stream of small but long period swell from the south and southwest will maintain small surf to the south facing shores throughout the forecast period. The return of the trade wind means the surf along the east facing shores will be on the rise between Friday and Saturday when the trades turn breezy. Expect surf to build to small to moderate heights. Surf along the east facing shores will be on the downtrend Monday as the trade winds weaken.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov