Hilo

Tonight: Mostly cloudy. Scattered showers in the evening, then occasional showers after midnight. Lows 66 to 73 near the shore to around 60 at 4000 feet. North winds up to 10 mph shifting to the northwest after midnight. Chance of rain 80 percent.

Monday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 81 to 87 near the shore to 67 to 72 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Monday Night: Mostly cloudy. Numerous showers in the evening, then occasional showers after midnight. Lows 67 to 73 near the shore to around 60 at 4000 feet. North winds up to 10 mph shifting to the northwest after midnight. Chance of rain 80 percent.

Kona

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows 67 to 75 near the shore to around 54 near 5000 feet. Light winds. Chance of rain 20 percent.

Monday: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 84 to 90 near the shore to around 69 near 5000 feet. West winds up to 10 mph. Chance of rain 40 percent.

Monday Night: Mostly cloudy with isolated showers. Lows 67 to 75 near the shore to around 55 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Tonight: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 66 to 73 near the shore to 59 to 66 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Monday: Partly sunny with scattered showers. Highs around 82 near the shore to 70 to 80 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy with scattered showers. Lows 67 to 74 near the shore to 61 to 67 near 3000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Kohala

Tonight: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 66 to 73 near the shore to 59 to 66 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Monday: Partly sunny with scattered showers. Highs around 82 near the shore to 70 to 80 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy with scattered showers. Lows 67 to 74 near the shore to 61 to 67 near 3000 feet. East winds up to 10 mph. Chance of rain 50 percent.

South Big Island

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Breezy. Lows around 76 near the shore to around 58 near 5000 feet. Northeast winds up to 20 mph.

Monday: Breezy. Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 87 near the shore to around 67 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Monday Night: Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Lows around 76 near the shore to around 58 near 5000 feet. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Puna

Tonight: Mostly cloudy. Scattered showers in the evening, then occasional showers after midnight. Lows 66 to 73 near the shore to around 60 at 4000 feet. North winds up to 10 mph shifting to the northwest after midnight. Chance of rain 80 percent.

Monday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 81 to 87 near the shore to 67 to 72 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Monday Night: Mostly cloudy. Numerous showers in the evening, then occasional showers after midnight. Lows 67 to 73 near the shore to around 60 at 4000 feet. North winds up to 10 mph shifting to the northwest after midnight. Chance of rain 80 percent.

Waikoloa

Tonight: Partly cloudy. Lows 69 to 75 near the shore to 54 to 59 above 4000 feet. Southeast winds up to 15 mph.

Monday: Mostly sunny in the morning then becoming partly sunny. Highs around 88 near the shore to 66 to 74 above 4000 feet. Northwest winds up to 10 mph.

Monday Night: Partly cloudy. Isolated showers in the evening. Lows 70 to 76 near the shore to 54 to 59 above 4000 feet. Light winds. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Moderate to locally breezy trades will continue this week as high pressure remains anchored well north of the state. A relatively dry and stable air mass will keep windward showers sparse and leeward areas mostly dry. Trades may ease briefly late this week before strengthening again next weekend as high pressure rebuilds to the north. Tropical systems far east of the state will be monitored, but pose no immediate impacts to the islands.

Discussion

Satellite shows mostly clear skies over most of the state this afternoon, while radar indicates isolated light showers in a few windward areas. Trade winds continue at 10 to 20 mph with gusts just over 30 mph in the usual windy spots.
A broad surface high centered well north of the state remains the dominate synoptic feature on our weather map, supporting moderate to locally breezy trades this week. Trade wind showers will remain limited as a relatively dry air mass persists. Model guidance suggests a slight increase of moisture Tuesday into Wednesday, but it will only lead to a slight increase in showers. Overall, we'll see isolated, light windward and mauka showers, with leeward areas remaining predominately dry.
Forecast confidence late in the week becomes increasingly dependent on the evolution of the tropical disturbances currently located well east of us. While deterministic and ensemble guidance suggests some westward progression, it remains too early to determine whether any of these systems or their associated moisture will influence the Hawaiian Islands. At this time, no changes to the sensible weather forecast are warranted, though these tropical features will continue to be monitored closely over the coming days.

Aviation

Moderate trades will continue through the forecast period. Outside of the occasional windward shower, expect largely VFR conditions across all sites.
No AIRMETs are in effect and none are anticipated for the forecast period.

Marine

The trade winds will ease tonight and Monday as high pressure north of the islands weakens, with the trades then holding at moderate speeds through Tuesday. The trades will restrengthen back to fresh and locally strong speeds Wednesday and Thursday as high pressure strengthens north of the island chain.
A south swell is expected to build tonight, then peak around the advisory level Monday night into early Wednesday. A High Surf Advisory will likely be required through this period. As this swell slowly fades during the middle of the week, a new long period south swell will arrive on Thursday, keeping surf elevated through next weekend.
Surf along north-facing shores will remain at flat to tiny levels through next weekend.
Surf along east facing shores will lower slightly Monday through Wednesday as the trades ease upstream of the islands. East shore surf should then build back close to seasonal levels late in the week through next weekend. Additionally, swell from Tropical Storm Elida may give a slight boost to east shore surf during the middle of the week.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov