The Army post's flag will be lowered at 4:30 p.m. when "Retreat" is sounded for the last time.
The property will be turned over to a 14-member force that will maintain and secure it while a government commission seeks developers for its 1,100-plus acres.
Fort Monmouth mission centered on communications ranging from carrier pigeons to sending electronic signals into space.
The Base Realignment and Closure Commission in 2005 decided to close the fort to save money. Closing costs rose from an estimated $782 million to nearly $2 billion by 2008.
Some 5,400 of the fort's 5,570 civilian and military jobs were sent to the Aberdeen Proving Grounds.