WAIMEA BAY — More monster waves are forecast today for O'ahu's North Shore, where thousands fought traffic and battled for parking yesterday to catch the kick-off of a swell that brought surf of up to 40 feet.

Forecasters say wave heights on the North Shore could further increase today, with occasional 50-foot sets along the outer reefs. And they warned that big waves still pose a danger to people, property and roads.

"This is still very serious business," said National Weather Service forecaster Robert Ballard.

The waves today could even be high and clean enough for the Quiksilver in Memory of Eddie Aikau big wave surf contest at Waimea Bay, which is held only when there are surfable waves with 40-foot faces (or about 20-foot waves measured Hawaiian-style, from the back of the wave). The invitational meet was last held in 2004.

Contest director George Downing estimated a 90 percent chance the contest will be held today.

Yesterday, the waves didn't live up to expectations — and fears — they would match a 1969 swell that brought waves of 50 feet that destroyed homes and washed away cars. But yesterday's surf did rise throughout the day, going from 15- to 18-foot faces at popular surf spots on the North Shore to more than 25 feet.

Ballard said there were a few, rare 40-footers spotted at Waimea Bay yesterday afternoon.

The waves kept lifeguards busy on the north- and west-facing shores.

Lifeguards conducted 2,500 "preventive actions" — warnings — to keep people out of the water, numerous assists and four rescues.

One of the rescues reportedly involved a pro surfer, who suffered injuries at Waimea Bay.

The surfer, whose identity was not released, is in his 40s and was taken to a hospital in serious condition after the 9:34 a.m. rescue. Responders did not disclose the surfer's injury, but when the surfer got out of the water he appeared to have a hurt left foot. He needed help to get to a waiting all-terrain vehicle.

NORTH SHORE JAM

Statewide, there were no reports of major damage, although sand did wash onto some roads.

The prospect of more big waves today means the North Shore probably will see a repeat of yesterday's crowds and bumper-to-bumper traffic.

North Shore residents don't relish that idea, but businesses do.

Up and down the coast yesterday, restaurants and shops were crammed.

Chris Kelly, hiring manager at the Surf n' Sea store in Hale'iwa, said business was "absolutely" up.

At Starbucks in Pupukea, the line was out the door yesterday morning.

And lunch wagons and restaurants were doing brisk business.

Hale'iwa Joe's saw "a good amount" of customers, said manager Rhoda Schwend.

People flocked to the North Shore throughout the day for the spectacle.

Well before daybreak, parking lots at beach parks were full and traffic was backing up.

Police directed traffic — and pedestrians — in places where crowds converged.

And people parked anywhere they could find a spot, including in the driveways of enterprising residents, where the going rate was around $10 a space.

One homeowner across from Waimea Bay asked $40 for the day. St. Peter and Paul Catholic Church near Waimea charged $5 to park, and by 9 a.m. had filled up its lot with more than 100 cars.

Waimea Bay proved the busiest spot on the North Shore, with people arriving before dawn hoping conditions would be right for the Eddie Aikau contest.

Tournament organizers deemed the conditions inadequate for the big-wave meet, and called off the contest around 7 a.m.

They'll decide this morning whether the contest will be held today.

By 8 a.m. yesterday at Waimea, people lined up four to six deep along the side of Kamehameha Highway to marvel at a handful of surfers braving the waves. The lower-than-expected wave heights disappointed some spectators, but they were more than enough for others.

Many said they would be back again today.

"It's beautiful — a little sloppy," said Carina Armendariz, of 'Ewa, as she stood on the beach at Waimea.

Joseph Moja, 65, of Kapahulu, said he had seen bigger waves from swells that received less publicity.

But, he added, the surf was still worth fighting through crowds and traffic to see.

Wahiawä resident Andress Carter agreed, saying the waves were plenty big to impress her.

"It's pretty amazing," she said.

Sprinkled in the crowds were lots of tourists.

Soly Kor, 34, of Austin, Texas, is in the Islands visiting friends and decided to come out to see the waves.

"So far, the waves are pretty awesome," he said.

By early afternoon, though, the crowds at Waimea Bay started to thin.

Shane Weldon, 26, of Sunset Beach, said he planned to return today.

He was crossing his fingers for bigger surf.

"It's not ready for the Eddie," he said. "The waves are kind of junk."

The swell is the result of storms off the Islands that are expected to produce high surf through midweek.

Lifeguards continue to warn of rogue waves, which can pop up unexpectedly and sweep people out to sea.

They also say only that only the most knowledgeable surfers should venture into high surf.

FEW CLEAN SETS

Yesterday morning, the waves along much of the North Shore were choppy and muddy, with few clean sets. Weather forecasters said northerly winds brought down wave heights and cut up ridable waves.

Few spots reported problems from the waves.

Water and some debris washed over the road near Laniäkea, Chun's Reef and Rockpile. No homeowners reported damage.

Greg Gerstenberger, manager at the Ke Iki Beach Bungalows near Pupukea Beach Park, said that waves lapped against the stairs at the property and came up to the deck early yesterday. "There was no damage. Just a lot of sand," he said.

Gerstenberger said waves at Ke Iki Beach yesterday were "pretty massive."

As of 11 p.m. yesterday, 11 people had reported to shelters opened on O'ahu, said John Cummings, spokesman for the city Department of Emergency Management.

Eight people were at the Leeward emergency shelter at Wai'anae District Park, all of whom live on the beach. Several people brought their pets, which are being allowed in the shelters for the first time. Three people were at the shelter at Lili'uokalani Protestant Church in Hale'iwa, Cummings said.

Cummings said there had been no reports of damage caused by the big waves as of 11 p.m.

"We still have volunteers that are driving the shorelines, giving us surf reports," he said earlier in the evening. "We haven't had any road closures. Minor debris and things, but that's about it so far."

Cummings said it's important that residents and beachgoers remain on alert until the danger is gone, which is expected to be tomorrow night.

“Until they drop the warning,” he said, “the hazard is still in place.”