Continued high-surf conditions and the annual crush of holiday beachgoers combined to keep North Shore lifeguards "extremely busy" on Christmas Day, an official said.

Ocean safety personnel made 18 rescues and took 1,325 preventive actions — such as warning people to stay on dry land — on Tuesday as waves reached heights of up to 20 feet, said Department of Emergency Services spokes­woman Shayne Enright.

One rescue involved a 27-year-old woman who injured her leg while surfing at Wai­mea Bay at about 2:45 p.m. Lifeguards used a personal watercraft to rescue her. Paramedics took the woman in serious condition to a hospital.

Paramedics were called to assist in three incidents.

Enright said thousands of visitors and residents ventured to North Shore beaches Tuesday. Officials took a combined 700 preventive actions at Wai­mea Bay and Lani­akea alone.

"Ocean safety wants everyone to have a safe holiday season, so we are asking the public to continue to check with lifeguards for the best information on the surf conditions," Enright said.

The National Weather Service issued a high-surf warning for the north-facing shores of Oahu, Kauai, Maui, Molokai and Niihau and the west-facing shores of Niihau, Kauai and Molokai through 6 a.m. today due to a large northwest swell.

A high-surf advisory was also in effect for west-facing shores of Oahu and north-facing shores of Hawaii island through 6 a.m. today.

The surf was expected to peak Tuesday night and gradually diminish through today.

The weather service predicts that winds across the islands will gradually increase and become easterly and southeasterly over the next couple of days. Showers will also increase through today, with rain possible over windward and mauka areas.