West Side

Today: Mostly sunny with isolated showers. Highs around 84. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 69 to 76. Northeast winds up to 15 mph. Chance of rain 20 percent.

Tuesday: Mostly sunny with isolated showers. Highs 81 to 86. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

South Side

Today: Mostly sunny. Breezy. Highs around 89. North winds up to 15 mph increasing to 10 to 25 mph in the afternoon.

Tonight: Breezy. Partly cloudy with isolated showers. Lows 68 to 77. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Tuesday: Mostly sunny. Highs around 89. Northeast winds 10 to 15 mph.

North Shore

Today: Breezy. Mostly sunny with isolated showers. Highs 80 to 85 near the shore to around 67 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with isolated showers. Lows around 72 near the shore to 50 to 55 near 5000 feet. East winds up to 20 mph becoming 10 to 15 mph after midnight. Chance of rain 20 percent.

Tuesday: Mostly sunny with isolated showers. Highs 79 to 85 near the shore to around 66 near 5000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Central Maui

Today: Breezy. Mostly sunny with isolated showers. Highs 82 to 90. Northeast winds up to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows around 71. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tuesday: Mostly sunny with isolated showers. Highs 82 to 89. East winds 10 to 15 mph. Chance of rain 20 percent.

Upcountry

Today: Sunny with isolated showers. Highs around 64 at the visitor center to around 70 at the summit. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 46 to 55. East winds up to 15 mph. Chance of rain 20 percent.

Tuesday: Sunny with isolated showers. Highs around 65 at the visitor center to around 69 at the summit. East winds 10 to 15 mph. Chance of rain 20 percent.

East Maui

Today: Breezy. Mostly sunny with isolated showers. Highs 80 to 85 near the shore to around 67 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with isolated showers. Lows around 72 near the shore to 50 to 55 near 5000 feet. East winds up to 20 mph becoming 10 to 15 mph after midnight. Chance of rain 20 percent.

Tuesday: Mostly sunny with isolated showers. Highs 79 to 85 near the shore to around 66 near 5000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Lanai City

Today: Sunny and breezy. Highs 74 to 83. East winds up to 15 mph shifting to the northeast up to 25 mph in the afternoon.

Tonight: Partly cloudy. Breezy. Lows 64 to 69. Northeast winds 10 to 25 mph.

Tuesday: Sunny. Highs 74 to 82. East winds 10 to 15 mph.

Kaunakakai

Today: Mostly sunny. Breezy. Highs 74 to 90. East winds up to 25 mph.

Tonight: Partly cloudy. Breezy. Lows 60 to 75. Northeast winds up to 25 mph becoming 10 to 20 mph after midnight.

Tuesday: Mostly sunny. Breezy. Highs 73 to 90. East winds 15 to 20 mph.

Detailed Forecast

Synopsis

High pressure ridging north of the Hawaiian Islands and a weak low propagating westward south of the islands will maintain stable weather conditions under moderate to locally breezy trades throughout the day. A shift in weather begins Tuesday, as a brief uptick in shower activity is expected as a batch of deeper moisture meanders into the vicinity of the state. For the latter end of the week through the weekend, expect periods of showers with increased cloud coverage associated with another batch of deep moisture.

Discussion

Broad area of high pressure and associated ridging remains quasi-stationary just north of the Hawaiian Islands as a weak low pressure system continues to propagate westward south of the state, producing a tight pressure gradient responsible for increased wind speeds. Stable conditions will maintain a relatively dry summer weather pattern with moderate to locally breezy trades through the day today, decreasing slightly through early Wednesday.
As the week progresses thereafter, trades increase slightly, as well as bring an uptick in shower activity and increasing cloud coverage as a batch of deeper moisture moves into the vicinity of the islands, primarily impacting windward and mauka areas, however, leeward areas may see some of the stronger trade wind showers. That said, these showers will dissipated as quickly as they arrive and overall moisture content will be limited.
Latest deterministic model guidance suggests unsettled weather conditions continue Thursday, persisting through much of the weekend. Guidance depicts a frontal system extending well north from the Gulf of Alaska and extending southward south of 40N. This front will perpetuate trades with deeper moisture ahead of the aforementioned high pressuring pinching off the tail end, pivoting this moisture toward the vicinity of the islands. The excess deeper moisture will coincide with the latter end of this week's progged temperature inversion levels, situated around the 7,000 foot elevation level, supportive of isolated to scattered showers throughout the day, and scattered to numerous showers overnight through the weekend. While the increase trade wind showers will higher coverage predominately across windward and mauka areas, it cannot be ruled out that leeward areas may see brief spillover.

Aviation

Moderate to locally breezy trade winds will continue through the forecast period. Limited clouds and showers will favor windward and mauka areas, with a slight uptick during the overnight hours. Conditions remain predominately VFR, with brief MVFR possible under passing showers.
No AIRMETS are in effect and none are anticipated through the forecast period.

Marine

Moderate to locally strong trades expected through this afternoon. As such a Small Craft Advisory (SCA) remains in effect for the windier channels and waters around Maui and the Big Island through 6PM tonight. A high to the north will weaken slightly on Tuesday allowing trades to ease. Winds should restrengthen by mid- week bringing back a SCA.
The recent small, medium period north swell will slowly decline today. Another medium period north swell is expected to arrive Thursday and may cause a slight bump in surf along north- facing shores.
A small, medium- to long-period south swell will keep surf along south-facing shores near the September averages gradually declining tonight through mid-week. A couple of very small reinforcements are expected throughout the week, though surf will remain small. A slightly larger, long-period swell is forecast to arrive in the islands Friday night, boosting south shore surf next weekend.
East facing shores will see typical trade wind generated energy throughout the forecast period.

Fire weather

Low humidity levels persist with sustained winds just under critical fire weather thresholds for a few hours this afternoon. Expect decreasing fire weather concerns beginning tomorrow onward through the forecast period as minimum humidity levels increase.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST this evening for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov