An approaching northwest swell has prompted weather officials to issue a high surf warning for the north- and west-facing shores of some islands effective Saturday evening.

Waves are expected to reach 25 to 35 feet for Niihau, Kauai and Oahu. The warning is in effect from 6 p.m. Saturday through 6 a.m. Monday.

Officials at the National Weather Service say the warning will likely be expanded Friday night or Saturday to include the other islands and expected the swell to produce “extra large to giant surf.”

The Quiksilver In Memory of Eddie Aikau holding period, which began on Dec. 1, 2013, ends today. None of the large winter swells to reach Oahu during that time met the contest’s requirement of clean, 40-foot wave face heights.

Beachgoers are advised that waves could sweep across portions of beaches and longshore and rip currents could make swimming hazardous.