A high surf advisory covers northern and western shores for most islands this weekend.

A northwest swell will build overnight and peak Saturday before declining early Sunday, the National Weather Service in Honolulu said this afternoon.

The advisory, which runs from 6 p.m. today until 6 a.m. Sunday, covers north- and west-facing shores of Niihau, Kauai, Oahu and Molokai and north-facing shores of Maui, forecasters said.

They said surf will rise to 10 to 15 feet along northern and western shores of Niihau and Kauai, and northern shores of Oahu, Molokai and Maui, while western shores of Oahu and Molokai will see waves from 8 to 12 feet through Saturday night.

Forecasters said beach-goers should expect strong breaking waves and rip currents making swimming difficult and dangerous.