Swell Matrix

Area Forecast Discussion

National Weather Service Honolulu Hi

1112 am hst Fri Sep 25 2026

Synopsis

Hurricane Nolo continues to slowly move to the north towards the Big Island, and is expected to make a turn to the west tonight. Moisture on the north side of Nolo will interact with the terrain of the Big Island and Maui, and could lead to significant flash flooding, particularly on the windward and southeast portions of the Big Island. Localized strong and gust winds are possible statewide, with the highest winds expected on the Big Island due to the proximity to Nolo.

Aviation

Gusty trade winds continue across most of the islands today with gusts peaking between 25 to 35 knots while gusts up to 40 knots are possible at the windiest sites. Winds are expected to remain gusty through the end of the TAF period. Confidence has decreased slightly in showers reaching the more northern islands given Nolo's more southerly track. That being said, trade showers are likely to continue across windward and mauka areas of the western islands today while heavier rain remains concentrated from Molokai down through the Big Island. The highest potential for moderate to heavy rain remains across the Big Island with reductions in ceilings and visibilities likely as shower activity becomes more frequent. This may result in periods of IFR to LIFR conditions in heavier showers on the Big Island today into tomorrow. Thunderstorm chances remain low for the Big Island. Temporary MVFR conditions are possible across the rest of the islands as showers develop.

AIRMET Sierra is in effect for mountain obscuration for windward areas of all islands today.

AIRMET Tango remains in effect for moderate turbulence downwind of island terrain due to breezy trade winds. Expect this to continue through the forecast period. It is possible that an AIRMET for sustained 30 kt winds will be needed for the Big Island by Saturday as Nolo passes to the south.

TC SIGMET Oscar series covers Hurricane Nolo, and interests should continue to monitor for updates to this SIGMET.

Marine

Hurricane Warnings around the Big Island and Tropical Storm Warnings around Maui County remain in effect as Hurricane Nolo inches northward. It is still forecast to turn west well before reaching the Big Island or adjacent nearshore waters, but strong winds and high seas can nonetheless be expected. South to southeast fresh swell emanating from Nolo will spread west across the southern nearshore waters as the system tracks west through early next week. The High Surf Advisory (HSA) for E and SE facing shores of the Big Island, Maui, and Molokai remains in effect and has been extended through Sunday. In addition, an HSA is now in effect for Kauai, Oahu, and Niihau beginning tonight due to strengthening trades. A small, long period NW swell fills in this weekend in maintenance of elevated surf along exposed shorelines into early next week.

Watches, Warnings, Advisories

Wind Advisory from 6 AM Saturday to 6 PM HST Sunday for Central Oahu-East Honolulu-Ewa Plain-Honolulu Metro-Kauai East-Kauai Mountains-Kauai North-Kauai South-Kauai Southwest-Koolau Leeward- Koolau Windward-Niihau-Oahu North Shore-Olomana-Waianae Coast- Waianae Mountains.

High Surf Advisory from 6 PM this evening to 6 PM HST Sunday for Kauai East-Kauai South-Koolau Windward-Olomana.

Flood Watch through Saturday afternoon for Big Island East-Big Island Interior-Big Island North-Big Island South-Big Island Southeast-Big Island Summits-Haleakala Summit-Kahoolawe-Kipahulu- Kohala-Kona-Lanai Leeward-Lanai Mauka-Lanai South-Lanai Windward- Maui Central Valley North-Maui Central Valley South-Maui Leeward West-Maui Windward West-Molokai Leeward South-Molokai North- Molokai Southeast-Molokai West-Molokai Windward-South Haleakala- South Maui/Upcountry-Windward Haleakala.

Tropical Storm Watch for Haleakala Summit-Kahoolawe-Kipahulu- Lanai Leeward-Lanai Mauka-Lanai South-Lanai Windward-Maui Central Valley North-Maui Central Valley South-Maui Leeward West- Maui Windward West-Molokai Leeward South-Molokai North-Molokai Southeast-Molokai West-Molokai Windward-South Haleakala-South Maui/Upcountry-Windward Haleakala.

High Surf Advisory until 6 PM HST Sunday for Big Island East-Big Island North-Big Island Southeast-Kipahulu-Maui Windward West- Molokai Southeast-Molokai Windward-South Haleakala-Windward Haleakala.

Hurricane Watch for Big Island East-Big Island Interior-Big Island North-Big Island South-Big Island Southeast-Big Island Summits-Kohala-Kona.

Tropical Storm Warning for Big Island East-Big Island Interior- Big Island North-Big Island South-Big Island Southeast-Big Island Summits-Kohala-Kona.

Tropical Storm Watch for Kaiwi Channel-Maalaea Bay-Maui County Leeward Waters-Maui County Windward Waters-Pailolo Channel.

Hurricane Watch for Alenuihaha Channel-Big Island Leeward Waters- Big Island Southeast Waters-Big Island Windward Waters.

Tropical Storm Warning for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters-Big Island Windward Waters.

Small Craft Advisory until 6 PM HST Saturday for Kauai Channel- Kauai Leeward Waters-Kauai Northwest Waters-Kauai Windward Waters-Oahu Leeward Waters-Oahu Windward Waters.

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