A high surf warning has been issued for the north- and west-facing shores of Niihau and Kauai, effective through 6 p.m. Thursday.

Weather officials said a large west-northwest swell is expected to spread down the island chain today, bringing dangerous surf to exposed north- and west-facing shores.

A high surf advisory has been issued for the north- and west-facing shores of Oahu and Molokai, the north-facing shores of Maui, and west-facing shores of the Big Island, also effective through 6 p.m. Thursday.

Surf is expected to build to 20 to 25 feet along the north and west-facing shores of Niihau and Kauai this morning, and continue through Thursday. Surf is expected to reach 18 to 22 feet along north-facing shores of Oahu, Molokai and Maui, and 12 to 16 feet along west-facing shores of Oahu and Molokai.

Expect ocean water occasionally sweeping across portions of beaches, strong, breaking waves, and strong rip currents. Breaking waves may occasionally impact harbors, weather officials said, making navigating the harbor channel dangerous.

Beachgoers, swimmers, and surfers should exercise caution and heed all advice given by Ocean Safety officials.