WILDWOOD, N.J. — At the Dolphin Gift Shop on the boardwalk, sales of T-shirts, beach balls, hats and sunglasses plunged over Labor Day weekend as customers fled from a storm that never arrived.

Dire forecasts of severe coastal flooding from Tropical Storm Hermine and Gov. Chris Christie’s declaration of a state of emergency for three coastal counties in New Jersey drove thousands of vacationers off the barrier island where Wildwood lies, leaving merchants with sharply lower revenue during what should have been one of the busiest weekends of the year.

“They called this the big storm that never happened,” Jarrod Eberle, an owner of the gift shop, said. “On Friday, there was a big exodus out of the town, and it’s been dead ever since.”

By late Monday morning, Mr. Eberle said he had taken in only about $5,000, down from the $15,000 or so he would expect on a normal Labor Day weekend.