A high surf advisory has been issued for most of Hawaii’s north- and east-facing shores, starting Friday morning, due to a north-northeast swell building tonight.

The National Weather Service says the swell will build tonight through Friday, boosting surf to advisory levels through the weekend.

The advisory, effective from 6 a.m. Friday to 6 p.m. Sunday, covers:

>> North-facing shores of Niihau, Kauai, Oahu, Molokai, Maui, and Hawaii island, with surf of 14 to 18 feet.

>> East-facing shores of Kauai, Oahu, Molokai, Maui, and Hawaii island, with surf of 10 to 14 feet.

The NWS warns of strong, breaking waves and currents along these shores, which will make swimming dangerous.

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

A small craft advisory for most Hawaiian waters — from northwest of Kauai to windward of Hawaii island — has also been issued, effective from 6 a.m. Friday to 6 a.m. Saturday.