A high surf advisory issued for the north- and west-facing shores of most Hawaiian islands has been extended through 6 p.m. today.

The National Weather Service says a moderate to large, west-northwest swell will remain elevated today before declining.

Surf of 12 to 16 feet is expected along the north-facing shores of Niihau, Kauai, Oahu, Molokai and Maui. Surf of 8 to 12 feet is expected along the west-facing shores of Niihau, Kauai, Oahu and Molokai.

Surf of 7 to 10 feet is expected along the west-facing shores of Hawaii island.

Weather officials warn of strong, breaking waves and strong currents, which will make swimming dangerous.

Forecasters expect a similar-sized northwest swell to build in late Tuesday and linger through Wednesday. An even larger swell is due in late Thursday into Friday, potentially bringing a high surf warning.

“Heed all advice from ocean safety officials,” said NWS. “When in doubt, don’t go out.”