West Side

Today: Mostly sunny. Breezy. Highs 79 to 86. Northeast winds 15 to 25 mph.

Tonight: Partly cloudy. Breezy. Isolated showers in the evening. Lows 67 to 74. East winds 10 to 20 mph. Chance of rain 20 percent.

Saturday: Mostly sunny. Isolated showers in the afternoon. Highs 79 to 84. East winds 10 to 15 mph decreasing to up to 15 mph in the afternoon. Chance of rain 20 percent.

South Side

Today: Sunny and breezy. Highs around 88. Northeast winds up to 20 mph increasing to 10 to 20 mph in the afternoon.

Tonight: Mostly clear. Lows 67 to 75. Northeast winds up to 15 mph.

Saturday: Mostly sunny. Highs around 88. North winds up to 15 mph shifting to the northeast in the afternoon.

North Shore

Today: Breezy. Mostly sunny with scattered showers. Highs around 82 near the shore to around 65 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows around 71 near the shore to around 51 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Saturday: Mostly sunny in the morning then becoming partly sunny. Breezy. Scattered showers. Highs around 82 near the shore to around 65 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Central Maui

Today: Sunny and breezy. Highs 82 to 88. Northeast winds 10 to 20 mph.

Tonight: Mostly clear. Lows 67 to 72. East winds 10 to 15 mph.

Saturday: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs 82 to 88. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Upcountry

Today: Breezy. Mostly sunny with isolated showers. Highs around 62 at the visitor center to around 69 at the summit. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows 42 to 54. East winds up to 25 mph. Chance of rain 20 percent.

Saturday: Breezy. Mostly sunny with isolated showers. Highs around 62 at the visitor center to around 67 at the summit. East winds up to 20 mph. Chance of rain 20 percent.

East Maui

Today: Breezy. Mostly sunny with scattered showers. Highs around 82 near the shore to around 65 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows around 71 near the shore to around 51 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Saturday: Mostly sunny in the morning then becoming partly sunny. Breezy. Scattered showers. Highs around 82 near the shore to around 65 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Lanai City

Today: Mostly sunny. Breezy. Highs 73 to 82. Northeast winds 10 to 20 mph.

Tonight: Partly cloudy. Breezy. Lows around 65. Northeast winds 10 to 20 mph.

Saturday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 72 to 81. Northeast winds 10 to 15 mph decreasing to up to 15 mph in the afternoon. Chance of rain 20 percent.

Kaunakakai

Today: Mostly sunny. Breezy. Highs 71 to 89. Northeast winds 10 to 20 mph.

Tonight: Partly cloudy. Breezy. Isolated showers in the evening. Lows 58 to 74. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Saturday: Mostly sunny. Highs 71 to 88. Northeast winds 10 to 15 mph.

Detailed Forecast

Synopsis

Moderate trades will continue through tomorrow, maintaining generally stable conditions across the Hawaiian Islands apart for isolated showers along windward and mauka locations. Trades will gradually weaken in response to an approaching frontal boundary and upper-level low advancing southward into the western islands late this weekend. This will bring unsettled weather across the state, particularly Kauai Sunday and Sunday night. Remnant moisture will continue to push over the state Monday and Tuesday. High pressure rebuilds thereafter through the remainder of the week.

Discussion

Broad area of high pressure well north of the islands will continue to be the driving force behind moderate trades across the state through tomorrow. During this time, generally stable conditions can be expected, with limited shower activity apart from isolated showers along windward and mauka areas.
Aside from a few isolated showers lingering around tonight, any spooky atmosphere will come from the ghouls and goblins, along with the princesses and superheroes out celebrating Halloween. Skies will remain mostly clear over leeward and interior areas of all islands, apart from partly to mostly cloudy conditions along windward slopes where the trade showers may persist. Otherwise, anticipate a rather pleasant night with overnight temperatures in the low- to mid-70s for most locations across the state.
Little change is expected during “candy recovery day” — better known as the day after Halloween — to start off the weekend. Moderate trades are progged to prevail under stable conditions, occasionally supporting windward and mauka clouds and showers.
However, a different story will be told during the latter half of the weekend, and one might say is the spookiest part of this forecast. The ambiance begins with trades gradually weakening in response to a southward advancing frontal boundary, shifting out of the southeast near Big Island and Maui, and northeast near Kauai and Oahu. The boundary, currently far north of the islands, will approach and is expected to reach Kauai late Sunday evening before meandering westward away from the islands. This boundary will have excess moisture escorted in with it, resulting in an increase precipitation chances across much of the state.
Immediately behind the frontal boundary, an upper-level low is progged to develop, pulling even more moisture northward across the state. The heaviest showers associated with the aforementioned low will focus around Kauai and Oahu late Sunday into Monday. A Flood Watch is being considered for Kauai during this time period, with particular emphasis on the northern and eastern sides of the island, but will be decided in a later forecast closer in time of the event.
Thereafter, high pressure rebuilds from Tuesday through the remainder of the week, allowing trades to reestablish across the region. Latest model guidance depicts another upper-level low and associated frontal boundary may advance in the vicinity of the Hawaiian Islands and could bring another round of unsettled weather. Further guidance will be necessary closer to the end to pinpoint any uncertainties, though, as this system will be monitored going forward.

Aviation

Moderate trades will persist through tomorrow, resulting in periods of MVFR conditions in isolated to scattered showers along windward and mauka areas, as well as across the Kona slopes of the Big Island during afternoon hours. Otherwise, VFR conditions prevail.
AIRMET Tango for TEMPO moderate turbulence is currently in place for Molokai, Maui, Lanai and Big Island between FL300 and FL450. The AIRMET will likely continue throughout the day, but may need to be amended for coverage and flight level.

Marine

High pressure to the northeast will maintain moderate to locally fresh trade winds through tonight. An overnight scatterometer pass showed Small Craft Advisory (SCA) level winds over the Alenuihaha Channel, but not quite so over the waters near South Point. Some of the high resolution models suggest winds near South Point will indeed reach SCA in the next 24 hours, so have boosted the winds there as well. Winds will be on the decrease Saturday as a front currently to the northwest of the island moves to the east and displaces the ridge. A SCA has been posted for the windier waters near Maui County and the Big Island through tonight. Winds are expected to remain below SCA levels until Tuesday or Wednesday.
The approaching front is expected to enter the offshore waters Saturday, with the possibility of gale force winds over the extreme northwest portion of the offshore waters Saturday night and Sunday. The front will also bring the possibility of thunderstorms to the offshore waters.
The small, long period NNW swell (330) began building at buoy 51001 around midnight, and should be reflected at the Waimea Bay buoy around midday. This will continue to keep surf slightly elevated along north ad west facing shores today. Surf is expected to increase rapidly tonight in response to a long period NNW swell (330) that is due to arrive, with the surf peaking at High Surf Advisory (HSA) levels Saturday morning. Surf will hold at HSA levels through Saturday night. A short period NNE swell, associated with an approaching front, is expected to arrive Sunday, and primarily impact the surf at the western end of the state where it will mix with the longer period NNW swell. This boost will likely bring HSA level surf back to Kauai and Oahu by Sunday afternoon. HSA likely Saturday for north and west facing shores, and then again possible for north and east facing shores of Kauai and Oahu by Sunday afternoon. A moderate to large swell is then possible around the middle of next week.
Surf along east facing shores will remain small to moderate through Saturday, and then be impacted by the short period NNE swell mentioned above. A small south swell will slowly fade through the weekend.

Fire weather

Increased relative humidity values and light to moderate trades will keep fire weather conditions below critical thresholds for the next several days. Temperature inversion heights near Maui and the Big Island will range from 7500 to 8500 feet elevation today.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Saturday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov