Karl "Kliff" Kramer collapsed May 19 while undergoing physical training at the department's fire academy.
Kramer died Saturday at Memorial Hospital, where he had been in intensive care since his collapse.
A spokeswoman for the Jacksonville Fire Department would not comment on the specifics of Kramer's death until an autopsy is conducted to determine the cause of his death.
"The training academy continually looks at the way they conduct exercise," spokeswoman Benny Seth said. "They continuously monitor the weather conditions, and those things will continue on as scheduled."
Other fire recruits told Channel 4's Bryan Kelly that the intense training makes everyone in the class close, "like a family."
"He had a real strong personality," Fire-Rescue cadet Mike Blcher said. "Whatever we were doing, he was always light hearted. We'll miss him."
Funeral InformationFuneral services will be held at 10 a.m. Thursday, June 2, at St. Matthew Lutheran Church, with Rev. Dr. David E. Imhoff, officiating.
Interment will be held in Arlington Park Cemetery.
The family will receive friends from 4 to 8 p.m. Wednesday, June 1, at Corey-Kerlin Funeral Home, 940 Cesery Blvd.
In lieu of flowers, the family requests memorials be made to the JFRD Ceremonial Memorial Engine Fund, 515 N. Julia St., Jacksonville, FL 32202