So much for fun in the sun.

A wet and not-so-wild Memorial Day capped a washout holiday weekend for the Big Apple, leaving Rockaway Beach empty during the unofficial start of summer except for diehard locals and frustrated business owners.

Sean Aiken, 49, who owns Seany Pizza on the boardwalk near Beach 98th Street, said the bad weather meant a massive financial loss for the whole peninsula.

“There’s only really four big, big holiday weekends: Memorial Day, Juneteenth, Fourth of July and Labor Day,” he said. “And everyone gets half their revenue from those four big weekends.

“A good Memorial Day will be like $12,000 for us, and this weekend will probably ring up $1,000.

“Everybody knows if you have a tough summer, you have a tough year,” he said. “But I’m optimistic that the weather will turn around.”

JFK Airport, a stone’s throw from the popular beaches of Rockaway and Jacob Riis Park, saw nearly 2 inches of rain since Friday, according to the National Weather Service.

The Post couldn’t find a single person at the local beaches Monday who wasn’t a Rockaway resident, even as the soggy weather subsided.

“This is the most people we’ve seen on the boardwalk in four days,” Aiken lamented Monday.

A sparse crowd meanwhile cheered the Rockaway Beach Day Parade, including lifelong local Ray Otton, 44, and his wife, Moe Otton.

“Rockaway won’t stop for the weather,” Ray Otton said. “We’re out to enjoy the parade, and with this weather, they need our support.”

Other locals also defied Mother Nature and gave area businesses a boost at the same time.

Christa Bauer, 56, sipped a beer with husband Chris Bauer, 47, and their King Charles spaniel Rose at boardwalk bar Bar 97.

“I said it was too cold but, he said we’re doing it,” she said of her hubby. “You can only do so much Netflix and chill.”

Few people other than surfers actually went onto the beaches or into the water, though.

Kevin Paskewitz, a 14-year-old Breezy Point resident, was the lone swimmer in the cold waves.

“It’s good for you,” he said about the cold water. “I go swimming all winter long. This is nothing for me.”

Justin, an 18-year-old lifeguard, bundled up in his chair, wearing two pairs of pants, two sweatshirts and a big heavy jacket.

When asked if he went into the water, he was emphatic: “Hell no! Too cold!”