Large winter surf kept lifeguards busy yesterday on O'ahu's north and west shores, and they expected another heavy day today with surf of 25 to 30 feet forecast for the North Shore.

Yesterday's waves led to warnings to hundreds of people and nine rescues.

And with surf above warning levels expected to continue through today and another large swell predicted for Sunday, beaches are likely to be busier than usual through the weekend with sightseers, traffic and beachgoers.

Yesterday began with eight- to 12-foot-face waves on the North Shore that rapidly increased to 15- to 20-foot faces, said Bryan Cheplic, spokesman for the city Emergency Services Department.

Lifeguards rescued seven people at North Shore beaches and warned or took preventive actions on 700 occasions, Cheplic said.

"The lifeguard will always try to be proactive rather than reactive, which explains the higher number of preventative actions versus the lower number of active rescues," Cheplic said in a press release.

On O'ahu's west shore, waves also reached 20-foot faces by yesterday afternoon, resulting in two rescues and 250 preventive actions, he said.

"It is not unusual to have high surf at this time of year, so the city's Ocean Safety and Lifeguard Services Division anticipates being busy and prepares accordingly," Cheplic said.

Waves on north-facing shores were expected to peak last night at 30 feet and continue between 25 and 30 feet through today, according to the National Weather Service. Surf on west-facing shores will be in the 15- to 20-foot range today, the weather service said, adding that east and south shore waves are expected to run about one to three feet today.

By Sunday, a large north-northwest swell is expected to hit the island, again bringing waves above the warning threshold, which is 25 feet for north-facing shores and 20 feet for west-facing shores, the weather service said. A small south swell is also expected on Sunday.

Cheplic warned beachgoers to always swim at a beach that has a lifeguard, talk to them about conditions, heed warning signs, never swim alone and to call a lifeguard or 911 when someone is in trouble.

Reach Eloise Aguiar at eaguiar@honoluluadvertiser.com.