A high surf advisory has been issued for the north-, west- and east-facing shores of the Hawaiian isles from Niihau to the Big Island, in effect through 6 a.m. Thursday.

The National Weather Service said surf is expected to reach heights of 14 to 18 feet along the north- and west-facing shores of Niihau and Kauai, and along north-facing shores of Oahu, Molokai and Maui, and 10 to 15 feet along the west-facing shores of Oahu and Molokai due to a northwest swell.

Meanwhile, surf of 8 to 10 feet is expected along east-facing shores of Kauai, Oahu, Molokai, Maui and the Big Island through early Thursday morning due to waves driven by strong easterly trades.

Expect strong, breaking waves, shore break, and strong longshore and rip currents, making swimming difficult and dangerous, weather officials said. Beachgoers, swimmers, and surfers should exercise caution and heed all advice given by Ocean Safety officials. Boaters should watch out for recreational surfers and body boarders utilizing harbor channels to access surfing areas.

Forecasters say high pressure north of the area will keep moderate to breezy trades in the isles through Saturday, with some clouds and passing showers favoring windward and mauka areas. Trades will begin to weaken late Saturday into early next week as a ridge of high pressure moves closer to the state.