Update: High surf advisory now in effect through Wednesday morning

3:49 a.m. Jan. 22 update: A high surf advisory is now in effect until 6 a.m. Wednesday.

Surf of 12 to 16 feet along north and west facing shores of Ni‘ihau and Kaua‘i is expected. Surf will slowly ease today, then trend back up tonight through Tuesday night.

Strong breaking waves and strong currents will make swimming dangerous.

3 p.m. Jan. 21 update: The high surf warning is now in effect until 6 a.m. Monday.

A large west-northwest (280-300 degrees) is very slow to ease this afternoon, so the warnings and advisory are extended through tonight. Surf heights should dip to advisory levels by Monday morning as the swell lowers.

Original post: A high surf warning goes into effect for north-facing shores of Kaua‘i and Ni‘ihau at 6 a.m. Saturday and will last till 6 p.m.

According to the National Weather Service in Honolulu, a large to extra-large west-northwest swell at 290-300 degrees will build down the island chain on Saturday and peak Saturday night and early Sunday. Due to the westerly component of the swell, leeward Big Island and portions of leeward Maui County will be affected by the large swell.

Due to the significant westerly component of this swell, the National Weather Service reports that shadowing could produce varying surf heights, and west-facing shores could experience more significant impacts.

Surf will build to 18 to 25 feet on Saturday and peak at 25 to 35 feet late Saturday night and early Sunday.

Along west-facing shores of Ni‘ihau, Kaua‘i, surf is expected to build to 12 to 20 feet on Saturday and peak at 15 to 25 feet Saturday night and early Sunday.

Beachgoers should expect ocean water surging and sweeping across beaches, coastal benches, and lava flows creating the potential for impacts to coastal properties and infrastructure, including roadways. Powerful longshore and rip currents will be present at most beaches.

Large breaking waves and strong currents may impact harbor entrances and channels causing challenging boat handling.