“It’s to the point that it looks like tailgating at MetLife stadium,” Matt Doherty, the Belmar mayor, said. “And I love tailgating at MetLife stadium, I really do. It’s just not what we’re looking for on the beach.”

On just about any given sunny weekend or weekday, evidence of the contagion is rampant.

With a tall, black pop-up cabana and the nasally vocals of Omi’s “Cheerleader” wafting across the beach, Andrea Julius and her friends from Philadelphia spread out toward the back of Jenkinson’s beach here to celebrate her 29th birthday.

“We like to be secluded but still connected to everyone, and this tent does it,” she said, while two friends volleyed a beach ball nearby.

They were, of course, there on a Tuesday, and the surrounding space allowed them some courtesy.

“We’re respectful back here,’’ Ms. Julius said. “All they have to do is tell us, and we’ll turn it down or take it down.’’

On the weekends the situation can get thornier.

Farther down the beach from the Weal spread, Rob Trumbo, 31, and Jessica Helfrich, 31, opted for foldable beach chairs, even though they usually bring along an umbrella, which wasn’t really necessary since the sun was hidden behind clouds.