Born in Bisbee, Arizona, Dyal attended the public schools of San Bernardino and Colton, California. He moved to San Bernardino, California, in 1917. Secretary to San Bernardino, County Board of Supervisors from 1941 to 1943. He served as a lieutenant commander in the United States Naval Reserve from 1943 to 1946. Postmaster of San Bernardino from 1947 to 1954. Insurance company executive from 1954 to 1961. He served as member of board of directors of Los Angeles Airways, Inc. from 1956 to 1964.
Dyal was elected as a Democrat to the Eighty-ninth Congress (January 3, 1965-January 3, 1967). He was an unsuccessful candidate for reelection in 1966 to the Ninetieth Congress. Regional director, San Francisco, California, Post Office Department from 1966 to 1969. Regional Programs Coordinator, United States Post Office Department from 1969 to 1971. Resided in Oakland, California, until his death there May 12, 1978. He was interred in Montecito Cemetery, Colton, California.