Swell Matrix

Area Forecast Discussion

National Weather Service Honolulu Hi

930 am hst Mon aug 17 2026

Synopsis

Tropical Storm Lala is continuing to move west of the state. Some lingering scattered showers will continue through the day. Trade wind pattern returns Tuesday with windward and mauka showers. Later this week winds may veer slightly southeast.

Aviation

Conditions have improved since yesterday. Lingering MVFR ceilings and showers will continue across windward areas of Kauai and the Big Island. A more typical trade-wind pattern over Oahu and Maui will focus brief MVFR ceilings and showers over windward and mountain areas. Overall, VFR conditions should prevail.

AIRMET Sierra for mountain obscuration will remain in effect for windward Kauai and the Big Island.

Marine

The center of Tropical Storm Lala has just exited the western edge of the offshore waters this morning as it continues to move west. Fresh to locally strong easterly trade winds will gradually build through the day from the east to west. A Small Craft Advisory (SCA) remains in effect for the windier waters and channels around Maui County and the Big Island through tonight. By midweek, trade winds will ease through the forecast period to gentle to fresh speeds across all coastal waters.

Surf along south facing shores will remain elevated today from a moderate medium to long period swell that has filled in overnight. Went ahead and bumped up the south shore surf slightly for this morning based on the latest buoy observations. Surf will likely peak today before slowly declining through midweek. Another long period south swell generated from gales just south and east of New Zealand will begin arriving late this week.

Surf along east facing shores will continue to decline today as Lala progresses further west of the state. East facing shores will remain small to moderate through the forecast period. North facing shores will remain tiny with only wind wave-driven chop in tandem with the declining east swell wrap. West facing shores will also remain tiny to small with some south swell wrap.

Watches, Warnings, Advisories

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

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