Julia H. Gunn was born in Lexington, North Carolina, and graduated from the high school department at Montreat College in Montreat, North Carolina. In 1941 she enrolled at the Woman's College of the University of North Carolina (now the University of North Carolina at Greensboro) and graduated in 1945 with a degree in chemistry.
Gunn joined the WAVES in June 1945 and reported to Hunter College in New York for basic training. She attended the weather school at Lakehurst, New Jersey, from September to December 1945, training as an aerographer’s mate and monitoring weather patterns. In early 1946 she was transferred to Navy Weather Central and worked in the Civilian Weather Bureau Building in Washington, D.C. Gunn was discharged in the summer of 1947.
After the war, Gunn did analytical chemistry work in the agronomy lab at North Carolina State University in Raleigh, North Carolina. In 1948 she married Larry Gunn. Throughout the 1950s she worked primarily in tax preparation, managing several H&R Block branches in the Greensboro area.