West Side

Today: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 78 to 84. East winds up to 15 mph. Chance of rain 40 percent.

Tonight: Partly cloudy with isolated showers. Lows 65 to 76. Northeast winds up to 15 mph. Chance of rain 20 percent.

Monday: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 78 to 84. Northeast winds up to 20 mph. Chance of rain 40 percent.

South Side

Today: Mostly sunny. Isolated showers in the afternoon. Highs around 85. North winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Tonight: Mostly clear. Lows 67 to 74. North winds 10 to 15 mph.

Monday: Mostly sunny. Breezy. Highs around 85. North winds 10 to 20 mph.

North Shore

Today: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 80 to 86 near the shore to around 65 near 5000 feet. East winds up to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 68 to 73 near the shore to around 48 near 5000 feet. East winds up to 15 mph. Chance of rain 70 percent.

Monday: Mostly cloudy. Occasional showers in the morning, then scattered showers in the afternoon. Highs 79 to 86 near the shore to around 65 near 5000 feet. Northeast winds up to 15 mph. Chance of rain 90 percent.

Central Maui

Today: Partly sunny with isolated showers. Highs 79 to 86. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Isolated showers. Lows 68 to 73. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Monday: Breezy. Partly sunny with isolated showers in the morning, then mostly sunny in the afternoon. Highs 79 to 86. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Upcountry

Today: Mostly sunny with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Highs around 61 at the visitor center to around 65 at the summit. Light winds becoming northeast up to 10 mph in the afternoon. Chance of rain 50 percent.

Tonight: Partly cloudy with scattered showers. Lows 41 to 52. East winds up to 10 mph. Chance of rain 50 percent.

Monday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 61 at the visitor center to around 66 at the summit. East winds up to 15 mph. Chance of rain 50 percent.

East Maui

Today: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 80 to 86 near the shore to around 65 near 5000 feet. East winds up to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 68 to 73 near the shore to around 48 near 5000 feet. East winds up to 15 mph. Chance of rain 70 percent.

Monday: Mostly cloudy. Occasional showers in the morning, then scattered showers in the afternoon. Highs 79 to 86 near the shore to around 65 near 5000 feet. Northeast winds up to 15 mph. Chance of rain 90 percent.

Lanai City

Today: Sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Highs 71 to 79. Northeast winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Lows 61 to 68. Northeast winds 10 to 15 mph.

Monday: Breezy. Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 71 to 80. Northeast winds 15 to 20 mph. Chance of rain 20 percent.

Kaunakakai

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 71 to 87. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 57 to 74. Northeast winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 20 percent.

Monday: Breezy. Mostly sunny with isolated showers. Highs 70 to 86. Northeast winds up to 20 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Light trade winds will continue today due to a weakness in the surface ridge north of the islands, allowing localized land and sea breezes to develop. Clouds and showers will favor windward slopes and waters during the early morning hours, with afternoon showers possible over leeward and interior areas where sea breezes develop. Moderate to breezy trades are expected to return during the first half of the week as the ridge strengthens north of the islands.

Discussion

Satellite imagery and the latest surface analysis show a shortwave trough approaching from the north, along with a weak surface trough nearby to the southeast. Falling upper heights, a surge of mainly low-level moisture, and a weakened or elevated inversion will support increasing shower coverage through the first half of the week.
The increase in showers will likely be most pronounced over the eastern end of the state through Monday, then gradually expand up the island chain by Tuesday. With lighter trades allowing sea breezes to develop today, some afternoon showers are possible over interior and leeward areas.
High-resolution guidance shows the low-level flow backing toward the northeast and increasing to moderate levels by Monday as the pressure gradient tightens. As moisture spreads across the state, windward shower coverage should increase, especially during the overnight and early morning hours from Monday through midweek. Breezy trades and a more typical trade wind pattern are expected to return during the second half of the week as the subtropical ridge restrengthens north of the area.

Aviation

Light trade winds will allow sea breezes to develop today. Some SHRA could be possible over inland and leeward areas. Winds should increase Monday with SHRA possible over windward and mauka locations especially in the overnight to early morning hours. MVFR conds will be possible in heavier SHRA, but generally VFR will prevail.
AIRMET Sierra is in effect for mtn obsc for windward Big Island. Conds should improve later this morning.

Marine

The trades will ease into the light to moderate range today as a front weakens the ridge north of the islands. The front will dissipate and the ridge will gradually strengthen north of the state Monday and Tuesday, allowing the trades to gradually strengthen back to moderate and fresh levels. High pressure north of the islands will strengthen further by the middle to latter part of next week, bringing fresh to strong trades back to the waters, with Small Craft Advisories likely being required for the typically windy waters around Maui and the Big Island.
The current long-period south swell will hold at advisory levels today, then gradually lower tonight and Monday as forerunners from a new long-period south swell begin to arrive. Surf is expected to briefly dip below advisory levels tonight and Monday, but will likely return to advisory levels Tuesday through Thursday, potentially peaking close to warning levels on Wednesday.
A combination of advisory-level surf and water levels hovering slightly above predicted levels could lead to some wave runup issues during this afternoons high tide cycle, with water sweeping across areas of beaches that typically remain dry. Water levels will gradually lower through the rest of the week.
Surf along north-facing shores will remain small through Monday, then trend slightly higher Tuesday through Friday as a pair of overlapping small north-northwest swells move through. North shore surf will drop back to nearly flat levels next weekend.
East shore surf will remain well below normal through Tuesday due to lack of trade winds over and upstream of the state. Surf will trend upward Wednesday and Thursday and hold close to seasonal levels Friday through next weekend.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST this evening 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