Sunday officially marked the beginning of the winter surf season around the west and north shores of Hawaii islands, the city Department of Emergency Services announced. 

“Today is opening day for our surf season here in Hawaii nei, and we have our first substantial swell out on our north and western shores,” said Jim Howe, operations chief for the city’s Ocean Safety Division on Sunday. “We are out there in full force today for the first time, and we are expecting large crowds, lots of folks, and a great season this year.”

Howe said that Sunday’s waves, which measured at 6 feet, or 12-foot faces, were not as big as expected, but he urged wave-riders and beach-goers to stay safe. A high surf advisoriy remains in effect for north and west shores of Oahu, Maui, Kauai and Molokai until 6 p.m. Surf on north-facing shores could reach up to 18 feet and 12 feet on west-facing shores.

“That is an ideal range for everybody to get out and start to get their feet wet as we kind of shift from our summer season into our very powerful North Shore surf season,” Howe said.

“But on any given day at any given spot we can have very, very, very dangerous, hazardous surf, especially for folks that are visiting or who are not real experienced with our conditions here at our beaches. So for those folks, we really want them to go (out) and understand that this is Hawaii, that this is the Super Bowl of surfing, that this is the North Shore — this is not Kansas.”

Howe said that the department will be releasing a full-season surf forecast in about two weeks. He advised that the current La Nina weather pattern will be shifting to an El Nino pattern this season, which will bring rougher surf.

“El Nino will mean that we have bigger surf and the storm systems will come close to shore,” he said. “So probably rougher conditions than we would have had last winter in totality.”

A small craft advisory is also in effect through 6 p.m. for waters within 40 nautical miles (46 statute miles) of Hawaii. The forecast includes scattered showers and winds of 23 mph through Tuesday night, and waves of greater than 10 feet.