Another huge swell is
expected here today

Surf will reach 25 to 30 feet
on north-facing shores

Back-to-back swells are expected to bring giant surf to Oahu's North Shore starting today, forecasters said.

A large northwest swell -- with waves between 25 and 30 feet -- will likely build overnight and peak near daybreak on the north-facing shores of Oahu and Kauai. The waves are expected to subside through the day and drop below 15 feet by tomorrow night, the National Weather Service said.

The weather service issued a high-surf warning yesterday in effect through tonight for north-facing shores of Oahu, Molokai and Maui, urging residents to stay out of the water and well away from the shore break.

NWS public service forecaster Pete Donaldson said today's swell is not expected to be as big as the one on Wednesday, which brought 40-foot surf to Waimea Bay.

But Oahu Civil Defense has its volunteers on alert in case waves wash over the roadway or into beachfront homes, spokesman John Cummings said.

A second swell is expected to raise surf heights again on Monday night, with waves likely reaching their peaks early Tuesday.

It is still too early for forecasters to estimate wave heights for that swell, but the weather service is expecting surf to get "almost as big as the last one" on Wednesday, Donaldson said.

"It will be pretty big," he said.