A high surf advisory for the north shores of most islands has been extended through Sunday evening.

The northwest swell that has generated advisory-level surf is expected to weaken Saturday but another north northwest swell will rapidly push surf back into advisory levels Saturday night and throughout Sunday, according to forecasters at the National Weather Service.

The advisory covers the north and west facing shores of Niihau, Kauai, Oahu and Molokai and the north-facing shores of Maui until 6 p.m. Sunday.

The swell is expected to generate 8- to 12-feet surf for north facing shores Saturday, rising to 18- to 22-feet surf overnight.  Surf on the west-facing shores is expected to be 6- to 8-feet, rising to 8- to 12-feet throughout Sunday.

Beachgoers are advised to heed all advice given by ocean safety officials.