Weather Forecast

Maui Weather Forecast for September 20, 2021

September 20, 2021, 7:15 AM HST
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Photo Credit: Tyler Rooke

West Side

Today: Breezy. Mostly sunny with isolated showers. Highs 81 to 88. Northeast winds up to 25 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then isolated showers after midnight. Lows 66 to 73. Northeast winds 10 to 25 mph. Chance of rain 50 percent.

Tuesday: Partly sunny in the morning then becoming mostly sunny. Breezy. Isolated showers. Highs 81 to 88. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

South Side

Today: Sunny and breezy. Highs around 87. Northeast winds 10 to 20 mph.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Breezy. Lows around 67. Northeast winds 10 to 20 mph.

ARTICLE CONTINUES BELOW AD

Tuesday: Mostly sunny. Breezy. Highs around 87. Northeast winds 10 to 25 mph with gusts to 45 mph.

North Shore

ARTICLE CONTINUES BELOW AD

Today: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 80 to 86 near the shore to around 67 near 5000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 63 to 70 near the shore to around 53 near 5000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Tuesday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 80 to 86 near the shore to around 66 near 5000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Central Maui

ARTICLE CONTINUES BELOW AD

Today: Breezy. Mostly sunny with isolated showers. Highs around 88. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Breezy. Isolated showers. Lows 65 to 71. East winds 10 to 20 mph. Chance of rain 20 percent.

Tuesday: Breezy. Mostly sunny with isolated showers. Highs around 88. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Upcountry

Today: Breezy. Mostly sunny with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Highs around 59 at the visitor center to around 56 at the summit. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Breezy. Scattered showers. Lows around 49 at the visitor center to around 46 at the summit. East winds 10 to 20 mph. Chance of rain 50 percent.

Tuesday: Breezy. Mostly sunny with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Highs around 55 at the visitor center to around 52 at the summit. East winds 10 to 20 mph. Chance of rain 50 percent.

East Maui

Today: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 80 to 86 near the shore to around 67 near 5000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 63 to 70 near the shore to around 53 near 5000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Tuesday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 80 to 86 near the shore to around 66 near 5000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Lanai City

Today: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs 73 to 82. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Breezy. Lows around 66. Northeast winds 10 to 20 mph.

Tuesday: Breezy. Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 73 to 82. Northeast winds 10 to 25 mph. Chance of rain 30 percent.

Kaunakakai

Today: Breezy. Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 79 to 89. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with isolated showers. Lows 63 to 74. East winds 10 to 20 mph. Chance of rain 20 percent.

Tuesday: Breezy. Partly sunny with isolated showers. Highs 79 to 89. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

A high pressure ridge north of the state will keep moderate to breezy trade winds across the region through Saturday. A typical trade wind weather pattern remains in the forecast with periods of passing showers focused mainly over windward and mountain areas of each island.

Discussion

Water vapor satellite imagery this morning shows an upper level trough just east of the main Hawaiian Islands. This upper trough will tend to produce passing showers over each island through Saturday. Satellite imagery and model guidance continue to show scattered to broken high level cirrus clouds drifting over the islands through Tuesday. These high level ice crystal clouds will enhance sunrise and sunset colors.
A high pressure system far north of the islands will continue to produce moderate to breezy trade winds into Saturday. Slight variations in the strength of the trade winds are expected from day to night, with decreasing wind speed trends for most land areas in the overnight hours. Decreasing trade winds are forecast on Sunday as the ridge north of the state weakens due to a cold front moving into the Central Pacific basin.
A low level easterly wave south of the islands will drift westward and brush through the Big Island from Monday afternoon into Tuesday. Increasing moisture with this disturbance will enhance showers along the east and southeast slopes of the Big Island, also adding a few more showers to the Kona slopes during the afternoon to early evening hours. A weak upper low moving in from the north will approach Kauai and Oahu on Tuesday and Wednesday. This system will move out fairly quickly and just continue to keep passing showers in the forecast.

Aviation

Moderate to breezy trades will carry periodic low clouds and showers over windward and mauka areas through this morning. Brief MVFR will be possible with any heavier showers, but otherwise prevailing VFR can be expected.
AIRMET Tango for lee turbulence remains in effect.

Marine

A ridge of high pressure N of the islands will maintain fresh to locally strong trades this week. Some subtle variations in wind speed can be expected through the period, with the potential for a slight increase Tuesday and Wednesday as the ridge strengthens and a trough passes S of the area. An ongoing Small Craft Advisory will likely remain posted for waters around Maui County and the Big Island for much of this week.
While surf will remain below High Surf Advisory levels along all shores this week, a trio of storm-force N Pacific lows will (or have) generate mid- to long-period NW to N swells that will arrive over the coming days. The first low is now weakening in the Gulf of Alaska, but it generated swell over the weekend that will arrive tomorrow and Wednesday, with peak open ocean swell heights approaching 5 feet. The second low will develop far NW of the area tonight and tomorrow, generating a similarly-sized (or slightly larger) NW swell that should arrive by the end of the week. The third low is expected to develop later this week, and may produce a NW to N swell that arrives in about a week or so.
As is typical in September, S hemisphere storm systems are still sending some swell our way, and a small boost in long-period S swell energy is expected around mid-week. The trade winds will deliver a steady supply of short-period wind waves to E facing shores through the week.

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov

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