A very large west-northwest swell expected to begin arriving late Saturday night will produce hazardous conditions for harbors with western exposures, the National Weather Service said.

A high-surf warning was in effect for north- and west-facing shores of Kauai, Oahu and Maui County, and for west-facing shores of the Big Island, through Monday afternoon.

Forecasters said the unusual western aspect of this swell will produce breaking waves at entrances of west-facing harbors and that strong to moderate surges inside harbors are likely.

Waves of 30 to 40 feet are predicted for north- and west-facing shores of Kauai. On Oahu, waves for those shores are expected to be 25 to 35 feet.

Wave run-up may affect Farrington Highway in Leeward Oahu, especially during high tides. Forecasters also warned of rip currents and coastal erosion.

Surf of 12 to 22 feet was expected for the Big Island’s west-facing shores.