Raymond Roth, 47, was last seen at about 3:30 p.m. Saturday, east of the beach's Field 6, police said.
Capt. Bruce Marx, commanding officer of the New York State Park Police on Long Island, which has jurisdiction over Jones Beach State Park, said authorities searched for Roth into the night Saturday and all day Sunday.
"We're just patrolling the beach front," Marx said of the search that resumed Monday morning. "I wish I could say more, but that's it."
The weekend searches included assistance from the Nassau County Police Department's aviation unit, and Marx said there is a chance it could be called to help again on Monday.
Roth was reported missing by his wife and son after he went swimming in an area of Jones Beach that lifeguards don't watch, police said.
Marx said Saturday that Roth's son said his father swam straight out and then he lost sight of him.
The family told police that Roth is a Jones Beach regular.
With Matthew Chayes and Alison Barnwell