Update, 8:45 p.m.
A high surf advisory has been upgraded to a high surf warning for south shores of all Hawaiian islands through Wednesday morning.
A large long period south swell will bring hazardous warning level surf to all south shores tonight and into Wednesday morning. The surf should subside to advisory levels by Wednesday afternoon through early Thursday morning.
Large breaking waves of 10 to 15 feet are expected this evening and rising to 12 t0 16 feet overnight. Large breaking waves of 10 to 14 feet are expected by Wednesday afternoon and subsiding to 7 to 10 feet by Thursday morning.
A high surf advisory has been issued for south shores of all Hawaiian islands, effective through 6 a.m. Thursday.
The National Weather Service says surf of 7 to 10 feet is expected to rise to 8 to 12 feet this afternoon as a long-period, south swell fills in.
Surf impacts will be moderate, but will include strong, breaking waves, shore break, and strong rip currents, which will make swimming difficult and dangerous. In addition, larger set waves may occasionally impact harbor entrances.
Beachgoers, swimmers and surfers should heed all advice from ocean safety officials.
The advisory may have to be upgraded to a warning this evening if surf heights come in higher than expected, forecasters said.
South shore surf is expected to decline below advisory level on Thursday, and return to the summer average by the weekend.
Surf on north and east shores is expected to remain low, at 1 to 3 feet and 2 to 4 feet, respectively, today through Wednesday. Surf on west shores will bump up from 6 to 8 feet this morning to 7 to 10 feet this afternoon through Wednesday.
Forecasters, meanwhile, expect moderate trades to continue through Thursday, with clouds and light showers favoring windward and mauka areas.
A small craft advisory is also in place for Maalaea Bay, Pailolo and Alenuihaha channels, and leeward and southeast waters of Hawaii island through 6 a.m. Wednesday.