A north-northwest swell arriving tonight could generate waves of 12 to 16 feet along north-facing shores through tomorrow, the National Weather Service said.

The "reinforcing swell" comes on the heels of one this weekend that prompted a high-surf advisory for all islands that was expected to remain in effect until this morning.

The new swell is forecast to build tonight, then begin dropping tomorrow night and Wednesday, said Sam Houston, lead forecaster for the National Weather Service.

Waves of 12 to 16 feet battered north-facing shores yesterday and were expected to fall to 10 to 14 feet today.

But the incoming swell arriving tonight could be even bigger, Houston said.

"The Monday night/Tuesday swell is showing that it might be even a little larger," he said.

Yesterday, Kauai officials warned beachgoers to stay out of North Shore waters, where the swell generated strong currents and waves with 15- to 20-foot faces from Hanalei to Kee.

Kauai officials called the conditions "extremely hazardous" and recommended that people use Anahola, Kealia, Lydgate, Poipu, Salt Pond and Kekaha beaches yesterday.

Today’s surf forecast calls for wave heights of 4 to 6 feet along west-facing shores; 2 to 4 feet along east-facing shores, with higher sets possible; and 2 to 4 feet along south-facing shores.