Waianae Coast

Today: Breezy. Partly sunny with scattered showers in the morning, then sunny in the afternoon. Highs 74 to 79. North winds 15 to 25 mph. Chance of rain 30 percent.

Tonight: Mostly clear. Breezy. Lows 62 to 68. Northeast winds 15 to 20 mph.

Friday: Sunny. Highs 74 to 79. Northeast winds 10 to 15 mph.

South Shore / Honolulu

Today: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny in the afternoon. Highs around 78. North winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Mostly clear. Lows around 65. Northeast winds around 15 mph.

Friday: Sunny. Highs around 77. Northeast winds around 15 mph.

East Honolulu

Today: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny in the afternoon. Highs 73 to 79. North winds 10 to 25 mph. Chance of rain 50 percent.

Tonight: Mostly clear. Breezy. Lows around 66. Northeast winds 15 to 20 mph.

Friday: Sunny and breezy. Highs around 75. Northeast winds 15 to 20 mph.

Ewa Plain

Today: Breezy. Partly sunny with scattered showers in the morning, then sunny in the afternoon. Highs 69 to 78. North winds 10 to 20 mph. Chance of rain 40 percent.

Tonight: Mostly clear. Lows 59 to 64. Northeast winds 10 to 15 mph.

Friday: Sunny. Highs 69 to 77. Northeast winds 10 to 15 mph.

North Shore

Today: Breezy. Partly sunny with scattered showers in the morning, then sunny in the afternoon. Highs 71 to 76. North winds 15 to 20 mph. Chance of rain 40 percent.

Tonight: Mostly clear. Lows 57 to 65. Northeast winds around 15 mph.

Friday: Sunny. Highs 71 to 76. Northeast winds 10 to 15 mph.

Central Oahu

Today: Breezy. Partly sunny with scattered showers in the morning, then sunny in the afternoon. Highs 69 to 75. North winds 10 to 25 mph. Chance of rain 40 percent.

Tonight: Mostly clear. Lows 57 to 63. Northeast winds 10 to 15 mph.

Friday: Sunny. Highs 68 to 75. Northeast winds 10 to 15 mph.

Windward Oahu

Today: Breezy. Partly sunny with scattered showers in the morning, then sunny in the afternoon. Highs 65 to 77. North winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Breezy. Lows 56 to 68. Northeast winds 15 to 20 mph.

Friday: Sunny. Highs 64 to 76. Northeast winds around 15 mph.

Koolau Leeward

Today: Breezy. Partly sunny with scattered showers in the morning, then sunny in the afternoon. Highs 63 to 77. North winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Mostly clear. Breezy. Lows 54 to 66. Northeast winds 15 to 20 mph.

Friday: Sunny and breezy. Highs 61 to 76. Northeast winds 15 to 20 mph.

Detailed Forecast

Synopsis

A cold front moving through the islands in Maui County this morning continues to spread showers and gusty winds as the frontal band passes through each island. Wind directions shift to a cooler and drier northerly direction after frontal passage today. Cool, moderate to breezy northeasterly winds on Friday will veer more easterly by this weekend. Another cold front will move down the island chain from next week Wednesday through Thursday, producing yet another round of wet rainy weather across the state.

Discussion

Shower bands moving through the islands along the leading edge of a cold front has produced a good amount of measurable storm total rainfall over Kauai and Oahu, ranging from 1/2 to over 2 inches in some locations over the past 12 to 18 hours. Expect these showers to continue with slightly decreasing rainfall amounts, over Molokai, Lanai and Maui this morning, and eventually into portions of the Big Island later today. Satellite imagery this morning shows the back edge of the cold frontal cloud band clearing out over Kauai and Niihau. Expect cooler and more stable northerly winds with decreasing shower trends spreading eastward through the morning hours. These improving weather conditions will spread to all islands later this evening.
The Wind Advisory for strong southerly wind gusts at lower elevations was cancelled this morning as the southerly wind gust threat diminishes statewide. However, strong upper level winds will continue over the highest mountain summits on Maui and the Big Island through the day. Strong and gusty winds just below advisory levels remains in the forecast for Haleakala National Park on Maui, just below our summit wind advisory thresholds. The highest summits of Mauna Kea and Mauna Loa on the Big Island will see the strongest winds with this event, and Wind Advisories remain in effect until 6 PM this evening for both summits. Brief periods of icing conditions are also possible on these higher elevation Big Island summits today.
High pressure building in behind the front will herald a return to drier and more stable northeasterly trade winds on Friday, becoming more easterly trade winds from Saturday into Sunday. This drier air moving in after frontal passage will produce much cooler temperatures for all islands, especially during the overnight hours when the drier atmosphere can more efficiently radiate heat into outer space. These lower humidity levels and cooler overnight to early morning temperatures will linger into the weekend.
Another round of wet weather remains in the long range forecast for the middle of next week. The latest extended model forecast guidance continues to show good agreement on another period of cloudy skies and wet weather as yet another cold front moves eastward down the island chain. Stay tuned as the island by island weather impacts from this next frontal band will likely evolve over time.

Aviation

A cold front will move through Maui County this morning, then push through the Big Island this afternoon. A line of showers with reduced cigs/vsbys can be expected in association with the front, with VFR conditions developing fairly quickly behind the front.
AIRMET Sierra remains in effect for mountain obscuration across Oahu and Maui County. Conditions should improve across Oahu later this morning.
AIRMET Tango remains in effect for low level turbulence over and downwind of the terrain of all islands. This AIRMET will likely remain in place through the day.
Tempo light icing is also mentioned in AIRMET Zulu. Conditions should improve later this morning.

Marine

A cold front over the central waters early this morning will continue to move from west to east across the coastal waters today. Southerly winds ahead of the front will transition to northwesterly behind the frontal passage. Meanwhile, an extra large northwest swell will generate large seas through Friday for exposed waters. The Small Craft Advisory (SCA) has been expanded to all Hawaiian waters and extended in time through Friday afternoon for combined seas above 10 feet, winds strengthening to 25 kt, or both. A high pressure system moving far north of the islands will bring back easterly trade winds across Hawaiian waters from Friday through Sunday. Winds will then become weaker and more southeasterly early next week as the next front approaches.
An extra large, medium to long period northwest (320-340 degrees) swell will fill in this morning, peak this afternoon into the evening, then slowly fade through Friday. Latest observations from NW Hawaii buoy 51001 early this morning show that wave heights have significantly increased to near 18 feet thus far. A High Surf Warning is now in effect through Friday for exposed north and west facing shores of Niihau, Kauai, Oahu, Molokai, and north facing shores of Maui. Additionally, a High Surf Advisory has been issued for west facing shores of the Big Island. This swell will gradually transition to become more northerly (350-010 degrees) as it fades into the weekend. Surf along north and west facing shores will then linger near advisory levels Saturday before another reinforcing northwest swell briefly boosts surf heights back to near warning levels on Sunday and Sunday night.
Surf along east facing shores will remain small, though will increase slightly by Friday as trades become re-established across the area. Additionally, some east facing shores sensitive to northerly swells may experience a slight uptick in surf heights this weekend as the fading northwesterly swell becomes more northerly. No noteworthy swells are expected for the next few days for south facing shores.

HFO Watches/Warnings/Advisories

High Surf Warning until 6 PM HST Friday for north and west facing shores of Niihau, Kauai, Oahu, Molokai, and north facing shores of Maui.
High Surf Advisory until 6 PM HST Friday for west facing shores of the Big Island.
Wind Advisory until 6 PM HST this evening for Big Island Summits of Mauna Kea and Mauna Loa.
Small Craft Advisory until 6 PM HST Friday for all Hawaiian waters.

Data Courtesy of NOAA.gov