Hilo

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 64 to 71 near the shore to 51 to 57 at 4000 feet. East winds up to 10 mph in the evening becoming light. Chance of rain 40 percent.

Saturday: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 79 to 87 near the shore to 65 to 71 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Saturday Night: Mostly cloudy with scattered showers. Lows 66 to 72 near the shore to 53 to 60 at 4000 feet. Light winds. Chance of rain 50 percent.

Kona

Tonight: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Haze through the night. Lows 71 to 76 near the shore to around 51 near 5000 feet. Light winds. Chance of rain 40 percent.

Saturday: Mostly sunny with isolated showers. Haze. Highs around 87 near the shore to around 70 near 5000 feet. Light winds. Chance of rain 20 percent.

Saturday Night: Mostly clear. Isolated showers in the evening. Lows around 74 near the shore to 50 to 55 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Tonight: Partly cloudy with isolated showers. Lows 63 to 71 near the shore to 55 to 62 near 3000 feet. East winds up to 15 mph in the evening becoming light. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers. Highs around 81 near the shore to 69 to 80 near 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Saturday Night: Partly cloudy with scattered showers. Lows 64 to 71 near the shore to 55 to 63 near 3000 feet. Light winds becoming east up to 10 mph after midnight. Chance of rain 40 percent.

Kohala

Tonight: Partly cloudy with isolated showers. Lows 63 to 71 near the shore to 55 to 62 near 3000 feet. East winds up to 15 mph in the evening becoming light. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers. Highs around 81 near the shore to 69 to 80 near 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Saturday Night: Partly cloudy with scattered showers. Lows 64 to 71 near the shore to 55 to 63 near 3000 feet. Light winds becoming east up to 10 mph after midnight. Chance of rain 40 percent.

South Big Island

Tonight: Mostly clear. Isolated showers in the evening. Haze through the night. Lows around 74 near the shore to around 55 near 5000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Saturday: Sunny with isolated showers. Haze. Highs 85 to 90 near the shore to around 70 near 5000 feet. Southeast winds up to 10 mph. Chance of rain 20 percent.

Saturday Night: Partly cloudy with isolated showers. Lows around 75 near the shore to around 56 near 5000 feet. East winds around 10 mph. Chance of rain 20 percent.

Puna

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 64 to 71 near the shore to 51 to 57 at 4000 feet. East winds up to 10 mph in the evening becoming light. Chance of rain 40 percent.

Saturday: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 79 to 87 near the shore to 65 to 71 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Saturday Night: Mostly cloudy with scattered showers. Lows 66 to 72 near the shore to 53 to 60 at 4000 feet. Light winds. Chance of rain 50 percent.

Waikoloa

Tonight: Haze in the evening. Partly cloudy with isolated showers. Lows around 74 near the shore to around 54 above 4000 feet. Northwest winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Saturday: Mostly sunny with scattered showers. Haze. Highs 85 to 90 near the shore to 67 to 73 above 4000 feet. North winds up to 10 mph shifting to the northwest in the afternoon. Chance of rain 40 percent.

Saturday Night: Mostly clear. Isolated showers in the evening. Lows around 74 near the shore to 52 to 57 above 4000 feet. Light winds. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Light to moderate trades will continue through next week, with localized land and sea breezes at times. Mostly dry and stable conditions will prevail, with the exception of a brief uptick in shower activity possible Sunday into Monday.

Discussion

The typical trade-wind producing high pressure far northeast of Hawaii remains displaced and weakened by a large area of low pressure. This synoptic setup will maintain light to moderate trades, with diurnal sea and land breezes developing across the state, particularly in leeward and interior areas.
Through much of the forecast period, mid-level ridging and dry air filtering across the region will limit shower activity, supporting a generally dry and stable pattern. Brief showers will mainly be confined to windward and mauka areas overnight into the morning hours, though sea breezes may bring isolated light showers to some leeward and interior areas each afternoon throughout the period.
An interruption to this pattern may come Sunday into Monday as a weak surface low tracks westward south of the Big Island. Moisture associated with this feature may clip the southern half of the island chain, bringing an uptick in showers, especially for windward Big Island and Maui. At the same time, an upper level low is forecast to stall northwest of Kauai, destabilizing the mid to upper atmosphere near the western end of the state. This combination of deeper tropical moisture and added instability, although not aligned perfectly, could allow for the slight enhancement of shower activity statewide, particularly from Sunday afternoon through Monday.
Conditions should return to a more typical stable hybrid trade wind and land-sea breeze pattern Tuesday onward, with light to moderate trades resuming and drier conditions prevailing.

Aviation

A ridge just north of the islands will maintain light to moderate trade winds into the weekend. Some localized daytime sea breezes and overnight land breezes are possible. A relatively dry airmass upstream of the islands will limit shower activity. The background trade wind flow will focus any clouds and showers to the windward sides of the islands, with some afternoon buildup over the west and central parts of the Big Island. Overall, VFR conditions will prevail with brief MVFR conditions possible in some of the clouds and showers.
No AIRMETs are in effect and none are expected.

Marine

A ridge of high pressure north of the state will gradually shift further south during the next day or so in response to a developing low far north of the state. As the ridge nudges closer to the islands our trade wind speeds will decrease with gentle to moderate trade winds expected this weekend into early next week. Winds should be light enough for localized sea breezes, especially across leeward waters.
Observations at nearshore PacIOOS buoys south of the islands show some reinforcing energy from the south in the 14-18 second energy bands this afternoon. The reinforcing energy should help maintain surf around the summer average through Saturday with a steady decline expected Sunday into Monday. Surf heights will return to background levels by early next week along south facing shores.
Surf along north facing shores will see a small, short period swell expected to arrive late this weekend. This swell will be overshadowed by longer period energy out of the northwest starting Monday night of next week. This swell should peak on Tuesday and could produce surf heights near the September average of 4 to 6 feet. Daytime ASCAT showed gale-force winds with the developing low far north of the state. This should send another reinforcing pulse out of the north around the same time the northwest swell arrives. A mix of north and northwest swells are expected next Tuesday through Thursday.
Below average surf is expected to continue along east facing shores due to gentle to moderate trade winds persisting through early next week.
Peak monthly high tides combined with water levels that are running higher than predicted may lead to minor flooding along the shoreline and in low-lying coastal areas toward the end of next week. Coastal flooding may be possible around the daily peak tide, which will be during the afternoon hours.

Fire weather

While critical fire weather thresholds were approached this afternoon across some leeward locations as relative humidities fell into the mid to upper 30 percent range, trade winds generally remained below criteria. The lighter trade winds are expected to be the main limiting factor through next week, helping to keep the state below critical fire weather thresholds, despite the high stability and drier conditions that are generally expected to stick around. Inversion heights will typically range between 6,000 to 8,000 feet.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov