High surf advisories have been issued for the north and east shores of most of the Hawaiian islands as a large north swell and rough trade wind-generated waves move in.
The National Weather Service said the high surf advisory will be in effect through 6 a.m. Monday for the north and east shores of Niihau, Kauai, Oahu, Molokai, Maui and the Big Island.
The large north swell is combining with a smaller short-period north-northeast swell, with waves expected to rise to 10 to 15 feet by late Saturday night, steadily building to 16 to 22 feet by Sunday afternoon.
East shores will rise to 10 to 15 late Saturday night and hold into Sunday, with rough and choppy conditions. Surf will be higher for east-facing shores with a northern exposure. East shore waves should lower as the the trade winds diminish Monday.
The combination of swells could also cause surges in Kahului and Hilo harbors late Saturday night through Monday and also produce breaking waves in the harbor entrances. Mariners should use caution when entering or leaving port and when mooring or launching vessels.