West Side

Today: Mostly sunny. Breezy. Scattered showers in the morning. Highs 76 to 87. Northeast winds 15 to 25 mph. Chance of rain 40 percent.

Tonight: Breezy. Cloudy with isolated showers. Lows 68 to 77. East winds 10 to 20 mph. Chance of rain 20 percent.

Sunday: Mostly cloudy. Isolated showers in the morning. Highs 76 to 87. Northeast winds 10 to 15 mph shifting to the east in the afternoon. Chance of rain 20 percent.

South Side

Today: Mostly sunny in the morning then becoming partly sunny. Breezy. Highs 77 to 88. Northeast winds 10 to 25 mph.

Tonight: Cloudy. Isolated showers in the evening. Lows 69 to 75. North winds up to 15 mph. Chance of rain 20 percent.

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

North Shore

Today: Cloudy and breezy. Occasional showers in the morning, then scattered showers in the afternoon. Highs 80 to 85 near the shore to around 65 near 5000 feet. East winds 10 to 20 mph. Chance of rain 90 percent.

Tonight: Cloudy and breezy. Numerous showers in the evening, then scattered showers after midnight. Lows around 72 near the shore to around 56 near 5000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Sunday: Breezy. Cloudy with scattered showers. Highs 80 to 85 near the shore to around 65 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Central Maui

Today: Partly sunny. Breezy. Scattered showers in the morning. Highs 80 to 87. Northeast winds 15 to 25 mph. Chance of rain 50 percent.

Tonight: Cloudy with isolated showers. Lows around 72. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Sunday: Mostly cloudy. Isolated showers in the morning. Highs 81 to 88. Northeast winds 10 to 15 mph decreasing to up to 15 mph in the afternoon. Chance of rain 20 percent.

Upcountry

Today: Partly sunny in the morning then becoming cloudy. Windy. Scattered showers. Highs 51 to 71. East winds 10 to 30 mph decreasing to 10 to 20 mph in the afternoon. Chance of rain 50 percent.

Tonight: Cloudy and breezy. Scattered showers and isolated thunderstorms in the evening, then isolated showers after midnight. Lows around 49 at the visitor center to around 45 at the summit. East winds 10 to 20 mph. Chance of rain 50 percent.

Sunday: Mostly cloudy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 52 to 69. East winds up to 15 mph. Chance of rain 50 percent.

East Maui

Today: Cloudy and breezy. Occasional showers in the morning, then scattered showers in the afternoon. Highs 80 to 85 near the shore to around 65 near 5000 feet. East winds 10 to 20 mph. Chance of rain 90 percent.

Tonight: Cloudy and breezy. Numerous showers in the evening, then scattered showers after midnight. Lows around 72 near the shore to around 56 near 5000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Sunday: Breezy. Cloudy with scattered showers. Highs 80 to 85 near the shore to around 65 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Lanai City

Today: Mostly sunny. Breezy. Highs 71 to 81. Northeast winds 10 to 25 mph.

Tonight: Cloudy. Lows 62 to 70. Northeast winds up to 15 mph.

Sunday: Mostly cloudy with isolated showers. Highs 70 to 80. Northeast winds up to 15 mph. Chance of rain 20 percent.

Kaunakakai

Today: Mostly sunny. Breezy. Isolated showers in the morning. Highs 71 to 88. East winds 10 to 25 mph. Chance of rain 20 percent.

Tonight: Breezy. Cloudy with isolated showers. Lows 59 to 75. East winds 10 to 20 mph. Chance of rain 20 percent.

Sunday: Mostly cloudy. Breezy. Isolated showers in the morning. Highs 70 to 87. East winds 10 to 20 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

An upper-level low will drift westward across the Big Island this morning, bringing enhanced shower activity and isolated thunderstorms across windward Big Island and the eastern coastal waters. This will increase humidity and help suppress fire weather concerns for much of the state. Trades will remain breezy through the morning, gradually decreasing this afternoon and persisting through the week. Another upper-level low moves into the vicinity of the islands by Wednesday, once again enhancing shower activity across the windward and mountain portions of the state through the remainder of the outlook period.

Discussion

Latest model guidance continues to support an upper-level low propagating west over the Big Island early this morning and meandering northwestward away from the islands later this weekend. This low will enhance shower activity and possible produce isolated thunderstorms this morning, especially along the windward and mauka areas of the Big Island, extending as far north as Maui. The heaviest shower activity developed last night, however, heavy showers remain possible along the Hamakua coastline of the Big Island throughout much of the day. A Winter Weather Advisory remains in affect for the Big Island summits to account for potential snow and ice accumulations through Sunday night.
The areal extent of the Red Flag Warning was trimmed to the leeward areas of Niihau, Kauai, and Oahu, and is in effect through 20z today (10pm HST) to account for 45 percent or lower relative humidity within those areas. Latest model guidance continues to suggest enhanced moisture will begin to move into the eastern end of the state today, which will increase relative humidity above critical fire weather thresholds. Please refer to the Fire Weather section below for further details.
Observations from Mauna Kea, as well as the 600 mb wind profile from the Hilo balloon sounding, showed trade winds across the Hawaiian Islands have decreased below advisory levels. Therefore, have opted to cancel the Wind Advisory for Maui County, Big Island, and the Big Island summits.
Trade wind speeds continue to weaken to a more light to moderate pattern from Sunday night through much of next week as the ridge north of the islands weakens in response to a passing cold frontal system well north of the islands. More stable conditions move back into the islands with brief passing showers favoring predominately windward and mauka areas during the overnight to early morning hours through Tuesday.
Latest model guidance showcases another wet and unstable trade wind pattern by mid-week. This will enhance overnight to early morning shower coverage statewide, just in time to add a little more spooky ambiance right before Halloween weekend.

Aviation

Trade winds will slowly decrease into moderate to breezy levels today, then continue to trend lower from Sunday onward as the high pressure ridge north of the islands weakens. An upper level disturbance will continue to produce some moderate clear air turb near the islands today along with enhanced shower activity, favoring the overnight to early morning hours. Isolated thunderstorms may continue to develop over the Big Island today.
AIRMET Sierra for tempo mountain obscuration above 2500 feet will continue this morning for north and east sections of most islands. These conditions may decrease in coverage briefly during the daylight hours, before expanding once again in the overnight hours.
AIRMET Tango remains in effect for moderate turbulence below 9000 feet over and south through west of island mountains, and from FL250 to FL350 for the whole state.

Marine

Large surface high pressure north of the state maintaining a tight pressure gradient over the islands has and is resulting in fresh to locally strong trade winds. A Small Craft Advisory (SCA) remains in effect for all coastal waters through the day to account for these winds and for elevated seas near 10 feet. As the high drifts eastward through the weekend, fresh trades will drop off to more water-wide moderate magnitudes. SCA-level winds will hold through Sunday in Maui County's channels and bays as well as south of Big Island. Winds will significantly lower to gentle to moderate speeds from late Sunday through Monday as a cold front impinges on the high as it moves into the eastern Pacific. Moderate winds through the middle of the week may strengthen back to more fresh speeds over west waters as a cold front approaches the northwestern offshore waters.
A reinforcing north-northwest (330 degree) swell, similar in size to the swell that peaked Thursday morning, will be passing around the islands through the afternoon. This swell will provide a slight boost to north and west-facing shore surf but heights will remain under advisory criteria during its morning peak. This swell will fall from this evening through early Monday. A quick hitting moderate size, short period north (360-010 degree) swell Wednesday originating from post-frontal strong breezes over the far north offshore waters will hold head high north-facing shore surf.
Fresh to strong trades has kept near 7 foot short period easterly wind wave chop alive along most east-facing exposures. Moderate to fresh easterly fetch over and just upstream of the islands, in tandem with some northwest swell wrap, will hold elevated sub- advisory eastern shore surf through tonight. Despite some northerly swell wrap on Wednesday, weakening trades will allow rough surf to subside to more seasonable heights next week.

Fire weather

Enhanced shower activity associated with a passing upper-level low meandering across the Big Island this morning has resulted in an increase of humidity, suppressing the Red Flag Warning for much of the state. The Red Flag Warning continues for Niihau, and leeward areas of Kauai and Oahu through this afternoon and was canceled for all islands in Maui County and Big Island due to increased humidity. Trade winds across the state remain breezy today, however, will gradually trend lower tonight to a more light to moderate speeds through the remainder of the week. Increased humidity values and decreasing winds will help maintain below critical fire weather thresholds for the rest of the weekend and into next week. Temperature inversion heights near Maui and the Big Island will range from 6,500 to 7,500 feet elevation today.

HFO Watches/Warnings/Advisories

Red Flag Warning until 6 PM HST this evening for Niihau, Kauai South, Kauai Southwest, East Honolulu, Honolulu Metro, Ewa Plain, Waianae Coast, Oahu North Shore, Central Oahu, Waianae Mountains.
Winter Weather Advisory until 6 AM HST Sunday for Big Island Summits.
Small Craft Advisory until 6 PM HST this evening for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Big Island Windward Waters.
Small Craft Advisory until 6 PM HST Sunday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov