Choppy seas made for poor surfing yesterday on the North Shore, where waves hit 15 to 30 feet at Ehukai Beach Park on the second day of the first big swell of the winter season.

"It’s definitely not good surf weather," said Ian Morrison, a meteorologist with the National Weather Service. "Very rough seas."

A high-surf warning will remain in effect until 4 p.m. today for all north- and west-facing shores of Niihau and Kauai and north-facing shores of Oahu, Molokai and Maui.

A new north-northwest swell is expected to arrive Sunday, possibly reaching unsafe levels, the weather service said.

Lifeguards reported surf breaking at 10 to 12 feet yesterday at Sunset Beach.

Surf heights were dropping after peaking Tuesday at 20 feet to 35 feet on Oahu and Kauai’s north shores.

Yesterday, city lifeguards using watercraft rescued three surfers at Haleiwa. The city Ocean Safety Division reported 280 preventative actions and 12 assists from Sunset Beach to Haleiwa. No one was injured.

The stormy conditions may have kept a lot of surfers out of the water.

Because of the rough conditions and strong north winds, it was difficult to determine the size of the waves, Morrison said.

A slow-moving cold front with rain passed through Oahu and Maui yesterday and last night, he said.

The Coast Guard reminded marinas and boaters to check that boats in port are secured, bilge pumps are working and all loose items are removed from decks.

For those boaters who choose to go out during potentially bad weather, the Coast Guard suggests filing a float plan. Mariners also should be prepared for the shock of sudden immersion and the disabling effects of cold water, and wear an approved life jacket, the Coast Guard said.

Boaters are also urged to have a VHF marine radio on board to monitor the weather.