West Side

Tonight: Partly cloudy. Isolated showers after midnight. Lows 65 to 74. East winds up to 10 mph. Chance of rain 20 percent.

Monday: Mostly sunny with isolated showers. Highs 75 to 87. East winds up to 15 mph. Chance of rain 20 percent.

Monday Night: Mostly clear. Isolated showers in the evening. Lows 65 to 74. East winds up to 15 mph. Chance of rain 20 percent.

South Side

Tonight: Mostly clear. Lows around 69. North winds up to 15 mph.

Monday: Sunny. Highs 77 to 89. North winds up to 10 mph.

Monday Night: Mostly clear. Lows 67 to 72. Northwest winds up to 10 mph.

North Shore

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows around 71 near the shore to around 53 near 5000 feet. Southeast winds up to 10 mph. Chance of rain 50 percent.

Monday: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 80 to 85 near the shore to around 67 near 5000 feet. East winds up to 20 mph. Chance of rain 40 percent.

Monday Night: Partly cloudy with isolated showers. Lows 69 to 74 near the shore to around 54 near 5000 feet. Southeast winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 20 percent.

Central Maui

Tonight: Mostly clear. Lows around 69. Northeast winds up to 15 mph.

Monday: Sunny and breezy. Highs 82 to 89. Northeast winds up to 20 mph shifting to the east 10 to 20 mph in the afternoon.

Monday Night: Mostly clear. Lows 67 to 72. East winds up to 15 mph.

Upcountry

Tonight: Partly cloudy with isolated showers. Lows around 44 at the visitor center to around 42 at the summit. East winds up to 10 mph. Chance of rain 20 percent.

Monday: Mostly sunny with isolated showers. Highs 52 to 69. East winds up to 10 mph. Chance of rain 20 percent.

Monday Night: Mostly clear. Scattered showers in the evening, then isolated showers after midnight. Lows around 45 at the visitor center to around 42 at the summit. East winds up to 15 mph. Chance of rain 40 percent.

East Maui

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows around 71 near the shore to around 53 near 5000 feet. Southeast winds up to 10 mph. Chance of rain 50 percent.

Monday: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 80 to 85 near the shore to around 67 near 5000 feet. East winds up to 20 mph. Chance of rain 40 percent.

Monday Night: Partly cloudy with isolated showers. Lows 69 to 74 near the shore to around 54 near 5000 feet. Southeast winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 20 percent.

Lanai City

Tonight: Partly cloudy. Lows 60 to 67. Northeast winds up to 10 mph in the evening becoming light.

Monday: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 69 to 80. Northeast winds up to 10 mph. Chance of rain 40 percent.

Monday Night: Partly cloudy. Isolated showers in the evening. Lows 60 to 67. Northeast winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Kaunakakai

Tonight: Partly cloudy. Lows 57 to 73. East winds up to 10 mph.

Monday: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 71 to 89. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Monday Night: Mostly cloudy in the evening then becoming mostly clear. Isolated showers. Lows 58 to 73. East winds around 10 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Light to moderate trade winds trade winds will shift out of the east to east-southeast Monday and Tuesday as a surface trough develops several hundred miles northwest of Kauai. Pockets of moisture moving along the trade wind flow will focus showers over typical windward slopes, while daytime sea breezes bring some chances for leeward showers on Monday and Tuesday afternoon. Trade winds will gradually strengthen Wednesday through Friday and likely be breezy next weekend.

Discussion

A rather stable, light to moderate trade wind flow remains in place this afternoon. A surface trough lies between Hawaii and somewhat strong high pressure farther north, causing the local pressure gradient and resulting trade winds to weaker than usual, and a mid-level ridge sitting over the islands is maintaining stable conditions with an inversion based near 7,000 ft. A narrow slot of reduced moisture is producing minimal rainfall along windward areas this afternoon, and aside from scattered showers over the Kona slopes of the Big Island and Ulupalakua area of Upcountry Maui, leeward areas are dry. Shower activity over leeward Maui will dissipate quickly around sundown and will diminish overnight on the Big Island. Shower activity over windward areas will remain light, with the exception of a possible uptick near Kauai and Oahu near sunrise.
Subtle changes are expected Monday and Tuesday. A surface trough will develop roughly 600 miles northwest of Kauai and cause local trade winds to veer out of the east to east-southeast, possibly causing afternoon leeward sea breezes to be more extensive on Kauai and Oahu. The inversion will weaken over these islands as well, suggesting higher chances for afternoon showers over leeward terrain.
Trade winds will strengthen and shift back to a more typical direction Wednesday through Thursday as low pressure to the northwest fills and surface high pressure builds far northeast of Hawaii. A stable, moderate to locally breezy trade wind flow will bring typical rainfall to mainly windward areas. Breezy trades are favored for next weekend.

Aviation

A hybrid sea breeze and light to moderate trade wind pattern will continue through tonight, with afternoon sea breezes giving way to land breezes tonight along terrain-sheltered western slopes. Trade wind speeds will gradually increase through the day Monday, becoming locally breezy over the eastern half of the island chain by Monday night. Relatively dry conditions will continue, with brief passing showers possible over windward and mountain areas, favoring the overnight through early morning hours. VFR conditions will prevail. No AIRMETs are in effect, nor expected through 24 hours.

Marine

A high pressure ridge will remain far north of Hawaii over the next several of days, then set up northeast of the state towards the end of the week. A trough developing northwest of the state will briefly cause the trade winds to veer toward the east- southeast on Monday. As the trough moves away, trades will gradually strengthen Tuesday into Wednesday with moderate to locally strong trade winds returning by the middle of the week. Small Craft Advisory could return to the typical windy areas around Maui County and the Big Island as early as Tuesday or Wednesday. As the ridge strengthens, widespread fresh to strong trade winds are possible this weekend.
The current south-southwest (200 degree) swell peaked last night into this morning and will continue to slowly decline through the middle of the week. A small south-southwest swell is possible Friday into the weekend.
Surf along east facing shores will remain moderate as the short- period northeast swell holds through Monday. Trade winds will gradually strengthen throughout the week, which will bring an increase of rough and choppy waves towards the second half of the week. Windswell will continue to increase over the weekend due to strong trade winds.
A trough located north of the state could produce small short- period energy out of the north Tuesday through the middle of the week.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov