Hilo

Tonight: Mostly cloudy early in the evening then becoming mostly clear. A 40 percent chance of showers early in the evening. Lows 61 to 68 near the shore to around 54 at 4000 feet. Southwest winds around 10 mph in the evening becoming light.

Tuesday: Sunny early in the morning, then partly sunny with a 50 percent chance of showers in the late morning and afternoon. Highs 80 to 86 near the shore to 66 to 72 at 4000 feet. Southwest winds around 10 mph shifting to the east in the afternoon.

Tuesday Night: Partly cloudy with a 20 percent chance of showers. Lows 59 to 64 near the shore to around 53 at 4000 feet. West winds up to 10 mph in the evening becoming light.

Kona

Tonight: Mostly cloudy early in the evening then becoming mostly clear. A 30 percent chance of showers early in the evening. Lows around 71 near the shore to 46 to 53 near 5000 feet. North winds around 10 mph in the evening becoming light.

Tuesday: Sunny early in the morning, then partly sunny with a 40 percent chance of showers in the late morning and afternoon. Highs 83 to 88 near the shore to around 69 near 5000 feet. Northeast winds around 10 mph shifting to the west in the afternoon.

Tuesday Night: Mostly cloudy early in the evening then becoming mostly clear. A 40 percent chance of showers early in the evening. Lows around 67 near the shore to 46 to 51 near 5000 feet. Northeast winds up to 10 mph.

Waimea

Tonight: Mostly cloudy early in the evening then becoming mostly clear. A 40 percent chance of showers early in the evening. Lows 61 to 69 near the shore to 54 to 59 near 3000 feet. East winds around 10 mph in the evening becoming light.

Tuesday: Sunny early in the morning, then partly sunny with a 50 percent chance of showers in the late morning and afternoon. Highs around 80 near the shore to 70 to 79 near 3000 feet. South winds around 10 mph shifting to the north in the afternoon.

Tuesday Night: Mostly cloudy early in the evening then becoming partly cloudy. Chance of showers early in the evening, then slight chance of showers in the late evening and overnight. Lows 59 to 65 near the shore to 53 to 59 near 3000 feet. Southeast winds around 10 mph. Chance of rain 50 percent.

Kohala

Tonight: Mostly cloudy early in the evening then becoming mostly clear. A 40 percent chance of showers early in the evening. Lows 61 to 69 near the shore to 54 to 59 near 3000 feet. East winds around 10 mph in the evening becoming light.

Tuesday: Sunny early in the morning, then partly sunny with a 50 percent chance of showers in the late morning and afternoon. Highs around 80 near the shore to 70 to 79 near 3000 feet. South winds around 10 mph shifting to the north in the afternoon.

Tuesday Night: Mostly cloudy early in the evening then becoming partly cloudy. Chance of showers early in the evening, then slight chance of showers in the late evening and overnight. Lows 59 to 65 near the shore to 53 to 59 near 3000 feet. Southeast winds around 10 mph. Chance of rain 50 percent.

South Big Island

Tonight: Mostly cloudy with a 30 percent chance of showers early in the evening, then clear in the late evening and overnight. Lows around 70 near the shore to around 50 near 5000 feet. Northeast winds 10 to 15 mph.

Tuesday: Sunny early in the morning, then partly sunny with a 40 percent chance of showers in the late morning and afternoon. Highs around 85 near the shore to around 68 near 5000 feet. North winds around 10 mph shifting to the south in the afternoon.

Tuesday Night: Mostly cloudy with a 40 percent chance of showers early in the evening, then clear in the late evening and overnight. Lows around 68 near the shore to around 49 near 5000 feet. Northeast winds around 10 mph.

Puna

Tonight: Mostly cloudy early in the evening then becoming mostly clear. A 40 percent chance of showers early in the evening. Lows 61 to 68 near the shore to around 54 at 4000 feet. Southwest winds around 10 mph in the evening becoming light.

Tuesday: Sunny early in the morning, then partly sunny with a 50 percent chance of showers in the late morning and afternoon. Highs 80 to 86 near the shore to 66 to 72 at 4000 feet. Southwest winds around 10 mph shifting to the east in the afternoon.

Tuesday Night: Partly cloudy with a 20 percent chance of showers. Lows 59 to 64 near the shore to around 53 at 4000 feet. West winds up to 10 mph in the evening becoming light.

Waikoloa

Tonight: Partly cloudy early in the evening then becoming clear. A 20 percent chance of showers early in the evening. Lows around 71 near the shore to 50 to 55 above 4000 feet. East winds around 10 mph in the evening becoming light.

Tuesday: Mostly sunny early in the morning, then a 40 percent chance of showers in the late morning and afternoon. Highs 84 to 89 near the shore to 65 to 73 above 4000 feet. Southeast winds around 10 mph shifting to the northwest in the afternoon.

Tuesday Night: Mostly clear. A 40 percent chance of showers early in the evening. Lows around 68 near the shore to 49 to 54 above 4000 feet. East winds up to 10 mph.

Detailed Forecast

Synopsis

Diminishing trade winds will remain light this week, with very little in the way of rainfall anticipated. A wetter and more active weather regime may develop by next weekend.

Discussion

Expect weakening trade winds to make way for prevailing light winds that will persist through the remainder of the work week. Upper ridging across Hawaii combined with a relatively dry environment will result in little rainfall expected over the next several days. Daytime sea breezes and nighttime land breezes will lead to interior cloud build ups throughout the day followed by clearing at night.
Confidence in the forecast decreases thereafter as there are hints of a pattern change across the islands despite some minor model discrepancies during beginning this weekend. Latest model guidance suggests an upper-level low will make way into the proximity of the islands toward the latter end of the week, increasing the instability across the region. Primary model discrepancy between models is the timing of the aforementioned low's arrival to the Big Island, with the GFS showcasing an arrival time of 36 to 48 hours sooner than the ECMWF.
The latest forecast has been derived from this GFS model run, exhibiting the upper-level low to arrive as soon as Saturday afternoon, enduring a wetter regime beginning Saturday and continuing into the first half of next week. Additional moisture moving in from the tropics from the southeast and the remnants of a backdoor front from the north will increase overall clouds and showers, especially once the upper-level low propagates southward across the state. These showers may become locally heavy at times and may even bring some snow during this period over the summits of Mauna Kea and Mauna Loa. However, given that the development of these features and their arrival to the islands are still several days out, confidence remains low with regards to location and impacts at this time.

Aviation

Light ESE trades will remain quite dry through the forecast period. Leeward areas will see clearing of any clouds with offshore land breeze development tonight followed by redevelopment of sea breezes again on Monday. VFR prevails.
No AIRMETs in effect.

Marine

A surface ridge to the north will weaken through the week as broad low pressure meanders well northwest of the state. Trade winds will steadily weaken through tonight with light to moderate east to southeast winds expected by Tuesday and likely persisting throughout the work week. Expect land and sea breeze conditions to become established near the coasts, where diurnally driven accelerations could lead to pockets of fresh breezes during the afternoons. For our typical windier channels around Maui and the Big Island, periods of fresh breezes will be possible during this time period. Breezy trade winds may return by this weekend as a high builds far north of the state.
Surf along north and east-facing shores will remain small through the first half of the week, primarily featuring small, short- period north-northwest swell. An upward trend is expected Wednesday into the second half of the week, as a short- to medium- period north-northeast swell arrives from a storm-force low forecast to develop around 1,000 nautical miles to the northeast from Tuesday through midweek. Heights could reach advisory levels for east-facing shores (10 ft faces) beginning late Wednesday night into Thursday, while north-facing exposures are expected to remain below advisory levels (15 ft faces). This will be a long- lived event, as the system slowly evolves and drifts northeastward late in the week. Guidance indicates a reinforcement from this system Friday into Saturday, which may coincide with the peak surf. A gradual downward trend is anticipated from Saturday through Sunday.
Surf along south facing shores will remain small, with predominantly a mix of short- to medium-period southeast and long-period south- southwest swells.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov