Born Daniel Sherwood Cohelan in San Francisco, Sherwood served briefly in the Canadian Armoured Corps (lying about his real age — 16), then enrolled in a radio class at Samuel Gompers School. He then joined the Merchant Marine. When he returned to San Francisco in 1944, his deep, resonant voice led to a job as announcer at KFRC, when Sherwood was only 19 years old. The job ended; and Sherwood was unemployed until he was hired by KQW, which was renamed KCBS in 1949, serving as an announcer and playing recordings. After being fired by KCBS on May 29, 1949, Sherwood worked at KROW in Oakland, California. Then, in 1953, he was hired by KSFO and remained there for three years. In 1956, he worked at KYA, then returned to KSFO the following year. He remained primarily at KSFO until 1969.