A high surf advisory has been issued for the north and west shores of Niihau and Kauai, and for the north shores of Oahu, effective until 6 p.m. today.

The National Weather Service expects peak surf of 14 to 18 feet along north-facing shores, and 8 to 16 feet along west-facing shores.

A moderate-sized, northwest swell lifted surf along north and west shores this morning, and is expected to slowly fade over the next few days.

Elevated surf is expected along many north and west shores this weekend, with another moderate swell expected to arrive Saturday.

In addition to strong, breaking waves, forecasters warn of strong currents, which will make swimming dangerous.

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