Lifeguards made 24 rescues and assists and issued 2,375 warnings because of high surf on the North and west shores, Ocean Safety Division officials said.

Lifeguards rescued a personal watercraft rider at about 3:30 p.m. today in Haleiwa at a surf spot called Avalanche after he got separated from the watercraft while in the surf lineup.

Surf heights averaged 20 to 30 feet on Oahu’s North Shore and 20 feet on the West Shore.

The National Weather Service forecasts the swell will subside through Friday. The surf will die down tomorrow to 12- to 16-foot faces for north shores, and 8 to 12 feet for west-facing shores and 4 to 7 feet on east-facing shores.

The Weather Service also issued a wind advisory for 6 a.m. tomorrow to 6 a.m. Thursday for strong and gusty east winds for all areas except Big Island summits.