The National Weather Service says a combination of a long-period northwest swell and shorter-period north-northwest swell will produce big waves today on north- and west-facing shores of Niihau, Kauai, Oahu and Molokai and north-facing shores of Maui.

Waves will be in the 15- to 18-foot range on north shores and 8 to 12 feet on west shores, but conditions are expected to be rough and choppy.
Surf is expected to remain elevated through tomorrow night, and a high-surf advisory is in effect until Friday morning.
A small-craft advisory is in effect for coastal waters of Hawaii. An earlier gale warning for waters beyond 40 nautical miles of the Islands has been lifted.
Meanwhile, ‘Cool northerly winds will deliver low clouds and a few light showers to windward slopes today, while leeward areas should see plenty of sun, especially in the afternoon,” the weather service says in its area synopsis.
“Trade winds will return tonight and (tomorrow) and will continue to focus clouds and light showers along windward slopes.”
High temperatures will be in the mid-70s and winds will be northerly at 15 to 25 mph.