Huge waves of up to 50 feet are expected to peak overnight on Kauai County north and west shore beaches, and north shores of Oahu, Molokai and Maui.
Forecasters expect the waves to gradually diminish through the weekend. But surf will remain at warning levels until about 6 p.m. Thursday.
The warning extends to west-facing shores of the Big Island, where waves should peak at 8 to 12 feet.
The National Weather Service is advising against travel to coastal areas of Kauai because of the potential hazards and emergency vehicle operations.
“These dangerous conditions mean that only highly experienced persons should enter the water,” the National Weather Service said. “Inexperienced persons should remain off beaches and adjacent beachfront areas. Large breaking surf, significant shorebreak and dangerous currents make entering the water very hazardous.”
Surf should lower to 15 to 25 feet on most shores Thursday and advisory-level surf is expected to continue through Saturday.
The Quiksilver in Memory of Eddie Aikau big wave surf contest was not held today, despite the size of the waves, because the swell is peaking at night.
Another northwest swell is expected to arrive Sunday and bring advisory-level surf through Monday. It will be followed by yet another swell on Wednesday.