The National Weather Service says a high surf warning and advisory will be posted for most of the state on Thursday at 6 a.m.
The high surf warning will be for the north facing shores of Kauai, Oahu, Molokai, and Maui. The warning also covers west facing shores of Kauai.
The high surf advisory will be for west facing shores of Oahu and Molokai.
Forecasters say a large northwest swell will arrive late Wednesday night causing surf to exceed advisory levels on Thursday. Surf is expected to rise around the warning level for north facing shores Thursday night into Friday.
Surf along north facing shores and west facing shores of Kauai will rise to 14-to-18-feet-tall Thursday and build to 20-to-25-feet-tall Thursday night. Surf along west facing shores will rise to 9-to-12-feet-tall Thursday and build to 14-to-18-feet Thursday night. The forecast surf heights are estimates of the front of the wave.
A high surf warning indicates that dangerous battering waves will pound the shoreline which will result in very dangerous swimming conditions and deadly rip currents.
A high surf advisory means that waves along the affected shores will be higher than normal. Beach goers are urged to stay out of the water and well away from the shore break due to hazardous wave action.