After peaking late Sunday night into early Monday morning, high surf off the islands’ north- and west-facing shores dropped in size throughout Monday but remained plenty big and hazardous enough that a National Weather Service high-surf warning remained in force through 6 a.m. today.

Lifeguards with the City and County of Honolulu Emergency Services Department Ocean Safety Division conducted six rescues and 2,445 preventive actions Monday on Oahu’s North Shore and four rescues and 808 preventive actions on Oahu’s West Side, said Dustin Malama, emergency services public information officer.

“Yesterday we had surf in the 40- to 50-foot face-value range, and this morning surf was in the 35- to 40-foot face-value range” at Waimea Bay, Ocean Safety Lt. Kerry Atwood said Monday. Because winds were lighter and the surf smaller, there were about 80 surfers at Waimea on Monday morning, he said.

“We had about five surfers at Waimea Bay that our rescue craft was able to assist, mostly surfers that broke their board or leash or are inexperienced, find themselves beyond their skill level and ask for a ride in,” Atwood said.

Monday was messy everywhere else on the North Shore, said Peter Cole, a champion big-wave surfer who lives in a beachfront home at Rocky Point, which lies between Ehukai Beach Park and Sunset Beach. “I checked Sunset this morning, and it was just a washing machine, not clean surf like you get with a long-interval groundswell, because we’re right in the fetch (the area the wind is blowing over) and that brings storm surf.”

Cole added he had seen some impact from the shore-wash on this wave-eroded stretch, where several beachfront properties have lost segments of their yards. “We’ve got some rocks showing that didn’t show before,” Cole said. “We usually lose beach when the swell is coming out of the west and out of the north, the white water coming from both directions.”

Waves sweeping over the shore imperilled sightseers, Atwood said. On Sunday, he said, alerted by the city Department of Emergency Services, lifeguards assisted a woman walking out on wet rocks at unguarded Sharks Cove before waves grabbed her.

Not only should spectators not swim, but they should “stay back from wet sand and wet rocks, abide by signs, don’t cross caution tape and view the surf from a guarded beach,” Atwood advised.

Surf along north- and west-facing shores was predicted to remain near advisory levels through the weekend due to a series of overlapping long-period northwest swells expected to roll in Wednesday, Friday and Saturday night.