Big waves kept lifeguards on Oahu’s north and west shores busy today during the first day of a high-surf warning that is expected to remain in effect until Thursday. 

Lifeguards made six rescues on the North Shore and three rescues on the island’s leeward side, the Honolulu Ocean Safety and Lifeguard Services Division said. 

None of the rescues required emergency treatment.

The National Weather Service in Honolulu today issued a high-surf warning through Thursday afternoon for north shores from Niihau to Maui. The western shores on Niihau and Kauai are also covered by the warning. 

With waves heights reaching 30 feet on the North Shore and 10 feet in Makaha, lifeguards had to issue hundreds of warnings for beach goers to stay away from the surf.

On the North Shore, lifeguards warned beach goers about dangerous surf 1,025 times and made six rescues by 4 p.m. today. On the leeward side, three people were rescued while lifeguards warned beach users of the surf 530 times.

A high surf advisory, meanwhile, is in effect for the eastern shores of all islands, west-facing shores on Oahu, and the north shore on the Big Island.

On the Big Island, authorities closed Onekahakaha, Kealoha, and Leleiwi Beach parks in Hilo today because of unusually high surf conditions, the county’s Civil Defense said.

Beach goers visiting the Keaukaha-Leleiwi area are asked to use caution because of dangerous surf conditions, the county said. 

On Oahu’s east side, the surf is six- to 10-feet high today at Sandy Beach and six- to 12-feet high at Makapuu, lifeguards said. 

The Weather Service said surf will remain in the 25-to-35 foot range through tomorrow along northern shores from Niihau to Maui and western shores on Niihau and Kauai.

“A powerful low passing well north of the islands has generated a large north-northwest swell that will continue through Thursday,” forecasters said. 

Surf along western shores of Oahu will be 12 to 18 feet, while the Big Island’s north shores will see 15-foot surf beginning today, forecasters predict.

A high-surf warning indicates that large waves will make for dangerous swimming conditions and deadly rip currents, they said. Forecast estimates are for the height of the face of the waves.