Waves as high as 40 feet could pound O'ahu's North Shore today with the arrival of the latest in a series of big-surf events this season.

The National Weather Service has issued a high surf warning for north- and west-facing shores today and continuing through most of tomorrow.

Forecaster Norman Hui urged people near the ocean to exercise caution.

"We had a pretty good-size storm northwest of us a few days ago, and it's generating this fairly large ocean swell that's coming into this island," Hui said. "We're going to be seeing some pretty big waves. The heights are high enough that it will produce waves above warning levels for the north- and west-facing shores on most islands."

Hui said the swell has a huge amount of energy that could send waves crashing across the highway and cause localized flooding.

"We might get a good wrap-around, so even the east shore of O'ahu is under a warning at this point. And the 2-foot high tide in the morning isn't going to help."

The weather service warning advises people to stay away from the shoreline in affected areas.

"Coastal residents need to remain alert to protect life and property," the warning said. "Be prepared for local road closures."