West Side

Tonight: Partly cloudy with isolated showers. Lows 64 to 74. East winds up to 15 mph. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers. Highs 74 to 86. East winds up to 15 mph. Chance of rain 20 percent.

Sunday Night: Partly cloudy with isolated showers. Lows 65 to 74. East winds up to 10 mph. Chance of rain 20 percent.

South Side

Tonight: Partly cloudy. Lows around 69. North winds up to 15 mph.

Sunday: Mostly sunny. Highs 77 to 88. North winds up to 15 mph.

Sunday Night: Mostly clear. Lows 67 to 72. North winds up to 15 mph.

North Shore

Tonight: Mostly cloudy with scattered showers. Lows around 71 near the shore to around 53 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs 80 to 85 near the shore to around 67 near 5000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Sunday Night: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 68 to 73 near the shore to around 54 near 5000 feet. Southeast winds up to 10 mph. Chance of rain 50 percent.

Central Maui

Tonight: Partly cloudy. Isolated showers after midnight. Lows 66 to 71. Northeast winds up to 15 mph. Chance of rain 20 percent.

Sunday: Mostly sunny. Breezy. Highs 81 to 88. Northeast winds up to 20 mph.

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

Upcountry

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 44 at the visitor center to around 41 at the summit. East winds up to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny in the morning then becoming mostly sunny. Isolated showers. Highs around 59 at the visitor center to around 61 at the summit. East winds up to 10 mph in the morning becoming light. Chance of rain 20 percent.

Sunday Night: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 45 at the visitor center to around 42 at the summit. East winds up to 10 mph. Chance of rain 40 percent.

East Maui

Tonight: Mostly cloudy with scattered showers. Lows around 71 near the shore to around 53 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs 80 to 85 near the shore to around 67 near 5000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Sunday Night: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 68 to 73 near the shore to around 54 near 5000 feet. Southeast winds up to 10 mph. Chance of rain 50 percent.

Lanai City

Tonight: Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Lows 59 to 67. Northeast winds up to 10 mph. Chance of rain 20 percent.

Sunday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 69 to 80. Northeast winds up to 10 mph. Chance of rain 20 percent.

Sunday Night: Partly cloudy with isolated showers. Lows 60 to 66. Northeast winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Kaunakakai

Tonight: Partly cloudy. Isolated showers after midnight. Lows 57 to 72. East winds 10 to 15 mph. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers. Highs 70 to 89. Northeast winds up to 15 mph. Chance of rain 20 percent.

Sunday Night: Mostly clear. Lows 58 to 73. East winds up to 10 mph.

Detailed Forecast

Synopsis

Light to moderate trade winds will persist during the next few days, becoming more easterly on Monday and Tuesday. 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 should be breezy next weekend.

Discussion

A stable, light to moderate trade wind flow will continue through Sunday. The trades will remain down from the past few days as the pressure gradient south of broad North Pacific surface high pressure stays relaxed due to a front far north of Hawaii. Aside from areas of thin high clouds, an upper-level trough parked over the region will have little effect, and a mid-level ridge will maintain fairly stable conditions with an inversion based between 6000 to 7000 ft. Diffuse bands of moisture moving along the trade wind flow will focus modest rainfall along windward slopes, and a band passing through late tonight and Sunday will mainly affect Kauai and Oahu. Aside from afternoon showers on the Big Island and Kauai, leeward areas should remain rather dry.
Subtle changes are expected Monday and Tuesday. The above mentioned upper-level trough will deepen west of the state and induce a surface trough several hundred miles northwest of Kauai. This will cause local trade winds to veer out of the east to east-southeast, possibly causing leeward sea breezes to be more extensive on Kauai and Oahu. The inversion will weaken over these islands, leading to higher chances for afternoon showers leeward and thicker high clouds over some islands.
Trade winds will strengthen Wednesday through Thursday as deep low pressure to the west 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.

Aviation

A hybrid sea breeze and light to moderate trade wind pattern will continue through Sunday night, with daytime sea breezes and nighttime land breezes along terrain-sheltered western slopes of each island. Brief passing showers are possible over windward and mountain areas, favoring the overnight to early morning hours. VFR conditions will prevail through the remainder of the weekend. No AIRMETs are in effect nor expected through 24 hours.

Marine

A high pressure ridge will remain far northeast of Hawaii over the next several of days, then set up north of the state during the second half of the week.
The current south southwest (200 degree) swell will bring large breaking surf to all south facing shores through the day Sunday, then gradually decline early next week. A High Surf Advisory is in effect for south facing shores through 6 PM HST Sunday. No other significant south swell sources expected through the remainder of next week.
Surf along east facing shores will remain moderate as the northeast swell declines this weekend. Trade winds will keep choppy, short period swell along east shores Monday and Tuesday, then will pick up as winds strengthen midweek.
A small, short period north swell will linger this week with tiny surf expected through most of the coming week.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST Sunday for Niihau, Kauai Leeward, Waianae Coast, Kahoolawe, Maui Leeward West, Kona, Kauai South, East Honolulu, Honolulu Metro, Ewa Plain, Molokai Leeward South, Lanai Leeward, Lanai South, Maui Central Valley South, South Maui/Upcountry, South Haleakala, Big Island South, Big Island Southeast.

Data Courtesy of NOAA.gov