(BIVN) – The entire State of Hawaii (except for Lanai) is under a High Surf Warning, which is in effect for north and east facing shores of Niihau, Kauai, Oahu, Molokai, Maui and the Big Island.

“A strong low pressure system over the northeast pacific ocean will generate a large north swell will build through the day on Wednesday,” the National Weather Service in Honolulu reports, “peak on Thursday and then decline Thursday night and Friday.”

The warning in effect until 6 a.m. HST Friday.

Surf heights will be 20 to 30 feet along north facing shores, and 10 to 15 feet along east facing shores of all islands, forecasters say.

“Expect ocean water occasionally sweeping across portions of beaches, very strong breaking waves, and strong longshore and rip currents,” the National Weather Service said Tuesday night. “Breaking waves may occasionally impact harbors making navigating the harbor channel dangerous.”

“Anyone entering the water could face significant injury or death,” the forecasters added. “Boaters should be aware of an increased number of surfers and body boarders utilizing the harbor channel to access surfing areas.”