Lyon was born in Pasadena, California were he attended high school with friend and fellow classmate Jackie Robinson. As a youth, he was a selected member of the United States Olympic swim team for the 1940 Summer Olympics in Tokyo, but the 1940 games were canceled due to the outbreak of World War II. Lyon graduated from Yale University in 1944 and that year he was captain of the Yale Bulldogs swimming and diving team with a season record of 10-0. He earned a master's degree from Stanford University in 1953.