Hilo

Tonight: Mostly cloudy. Numerous showers in the evening, then scattered showers after midnight. Lows 60 to 70 near the shore to 51 to 57 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 70 percent.

Monday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 81 near the shore to around 67 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows 61 to 69 near the shore to 50 to 56 at 4000 feet. East winds up to 10 mph in the evening becoming light. Chance of rain 40 percent.

Kona

Tonight: Partly cloudy. Isolated showers in the evening. Lows around 72 near the shore to around 51 near 5000 feet. Light winds. Chance of rain 20 percent.

Monday: Mostly sunny. Scattered showers in the afternoon. Highs 83 to 88 near the shore to around 68 near 5000 feet. Southwest winds up to 10 mph shifting to the west in the afternoon. Chance of rain 40 percent.

Monday Night: Mostly clear. Lows 69 to 74 near the shore to 48 to 53 near 5000 feet. Light winds.

Waimea

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows 61 to 71 near the shore to 54 to 62 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Monday: Mostly sunny with isolated showers. Highs 64 to 83. East winds up to 15 mph. Chance of rain 20 percent.

Monday Night: Partly cloudy. Isolated showers in the evening. Lows 61 to 70 near the shore to 54 to 61 near 3000 feet. Southeast winds up to 10 mph. Chance of rain 20 percent.

Kohala

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows 61 to 71 near the shore to 54 to 62 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Monday: Mostly sunny with isolated showers. Highs 64 to 83. East winds up to 15 mph. Chance of rain 20 percent.

Monday Night: Partly cloudy. Isolated showers in the evening. Lows 61 to 70 near the shore to 54 to 61 near 3000 feet. Southeast winds up to 10 mph. Chance of rain 20 percent.

South Big Island

Tonight: Partly cloudy. Breezy. Isolated showers in the evening. Lows around 73 near the shore to around 54 near 5000 feet. Northeast winds up to 20 mph becoming 10 to 15 mph after midnight. Chance of rain 20 percent.

Monday: Sunny and breezy. Isolated showers in the afternoon. Highs around 86 near the shore to around 68 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Monday Night: Mostly clear. Lows around 73 near the shore to around 54 near 5000 feet. East winds 10 to 15 mph shifting to the northeast after midnight.

Puna

Tonight: Mostly cloudy. Numerous showers in the evening, then scattered showers after midnight. Lows 60 to 70 near the shore to 51 to 57 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 70 percent.

Monday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 81 near the shore to around 67 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows 61 to 69 near the shore to 50 to 56 at 4000 feet. East winds up to 10 mph in the evening becoming light. Chance of rain 40 percent.

Waikoloa

Tonight: Partly cloudy. Lows around 73 near the shore to 50 to 55 above 4000 feet. Southeast winds up to 10 mph.

Monday: Sunny. Isolated showers in the afternoon. Highs around 85 near the shore to 65 to 72 above 4000 feet. East winds up to 10 mph shifting to the north in the afternoon. Chance of rain 20 percent.

Monday Night: Mostly clear. Lows around 72 near the shore to 49 to 54 above 4000 feet. Light winds.

Detailed Forecast

Synopsis

Light to moderate trade winds will continue through the next few days, followed by light east to southeasterly winds mid-week, and increasing southeasterly winds Friday into next weekend. Shower chances will trend down through the first half of the week as a front passes well north of the islands. By next weekend, an approaching front could result in southerly flow and increased showers, particularly over the western end of the state.

Discussion

This afternoon, light to moderate trade winds are prevailing across the island chain as a weakened surface high remains centered well northeast of the state. Latest satellite and radar imagery shows only a few light showers favoring windward and mountain locations, in addition to afternoon cloud buildups and light showers along the Kona slopes of the Big Island.
As a trough aloft moves farther east away from the islands tonight, ridging will build back into the region, increasing stability. Additionally, even drier air can be seen on CIMSS MIMIC Layer Precipitable Water imagery just east of the islands, and this drier air is expected to move overhead tonight into Monday. The increasing stability and drier air will result in an overall downward trend in windward and mauka showers through the next couple of days. Light to moderate trade winds will continue through mid-week, as a couple of cold fronts move across the North Pacific, well north of the islands, and keep the surface high to our northeast in a weakened state throughout this time.
On Wednesday, another front will approach the islands but pass north of the state. As this feature approaches, the surface ridge to our northeast will be displaced southward, with the ridge axis extending directly over the main Hawaiian Islands. Expect lighter east to southeasterly winds as the front approaches from the northwest. Not much change is expected regarding shower chances throughout this time, however, as the ridge over the islands will maintain fairly stable conditions with subsidence temperature inversion heights hovering around 6,000 to 7,000 feet. As winds decrease mid-week, daytime sea breezes and overnight land breezes are likely to develop over sheltered areas.
Model guidance continues to indicate that a much more robust surface low will move across the North Pacific next weekend, and its trailing cold front could impact at least portions of the main Hawaiian Islands Saturday into Sunday. As this front approaches the western islands, southerly flow has the potential to draw deeper tropical moisture northward, producing hot and humid weather and increasing showers trends. Latest guidance depicts the approaching cold front stalling and then dissipating near Kauai late next weekend, though confidence remains low at this time. Details will become more clear as the time approaches.

Aviation

Moderate trades deliver limited showers windward and mauka and give rise to expanding sea breezes in sheltered locales during peak heating today. Brief showers will translate to isolated MVFR, but VFR prevails.
No AIRMETs in effect.

Marine

Gentle to locally fresh easterly trades will prevail through Thursday as a surface ridge sits far northeast of the islands. Expect an increase in southeasterly winds on Friday and Saturday as a front approaches from the northwest. Winds over the typically windy waters around the Big Island and Maui County will be borderline Small Craft Advisory (SCA) strength through Monday. Otherwise, winds should remain below SCA criteria through the period. However, combined seas over 10 ft (SCA criteria) remain possible Wednesday into Thursday and again on Saturday as a series of large northwest swell arrive.
The current moderate, long period, northwest swell (320 degrees) continues to subside this afternoon, with the Waimea Bay buoy currently around 6 ft at 13 seconds. This swell will continue to decline through tonight so the High Surf Advisory (HSA) along north and exposed west facing shores from Kauai to Maui has been cancelled. North shore surf will be well below seasonal average on Monday and Tuesday. A potentially larger northwest swell is expected to arrive Wednesday and peak into Thursday. If current guidance holds a HSA will be needed during this time, with warning level surf possible. This swell will decline Friday and Saturday, though there are high odds for a larger west-northwest swell later this weekend.
As trade winds weaken over the next couple of days, surf along east facing shores will decline and will be well below seasonal average through much the week. South shore surf will be tiny through the week.

Fire weather

Critical fire weather conditions are not expected throughout the next few days. Relative humidity levels are expected to decrease on Monday as stable, drier air settles over the state. However, wind speeds are expected to stay below critical thresholds. Relative humidity values will rebound throughout the rest of the week as winds remain light to moderate.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov