Born in
Hochheim, Texas, St.Clair went to school in
Yoakum, Texas, and graduated from
Yoakum High School. He attended the
University of Texas and later studied conducting with
Gustav Meier at the
University of Michigan and
Leonard Bernstein at
Tanglewood. He was Music Director of the
Ann Arbor Symphony Orchestra (Michigan) from 1985 to 1992, and of the
Cayuga Chamber Orchestra (Ithaca, New York) from 1986 to 1991. Beginning in 1986, he was an assistant conductor with the
Boston Symphony Orchestra. In 1990, he was a recipient of the
Seaver/National Endowment for the Arts Conductors Award. In January 1990, St.Clair guest-conducted the
Pacific Symphony for the first time. St.Clair became the music director of the Pacific Symphony as of the 1990–1991 season. During his Pacific Symphony tenure, he and the orchestra have commissioned and recorded several works, including
Richard Danielpour's
An American Requiem (Reference Recordings) and
Elliot Goldenthal's
Fire Water Paper: A Vietnam Oratorio (Sony Classical) with cellist
Yo-Yo Ma. Other recordings include "Radiant Voices" and "Postcard" by composer in residence
Frank Ticheli (Koch International Classics), and the two piano concertos of
Lukas Foss (harmonia mundi). The orchestra and St.Clair host an annual festival of American composers, including "Uncharted Beauty: The Music of Lou Harrison" (2005–2006), "Los Sonidos de México" (2006–2007), and "The West — Music inspired by the American Frontier" (2007–2008). St.Clair stood down from the Pacific Symphony post in 2025 and now has the title of music director laureate for life with the orchestra. In Europe, St.Clair was principal guest conductor of the
Radio-Sinfonieorchester Stuttgart from 1998 to 2004, where his work included a three-year recording project of the
Villa–Lobos symphonies. He became
Generalmusikdirektor (General Music Director, or GMD) of the
Staatskapelle Weimar in 2005, a post he held for three years. In 2008, he took up the post of GMD of the
Komische Oper Berlin, He held the Costa Rica post until 2023 and now has the title of conductor emeritus of the orchestra, since 2025. St.Clair first guest-conducted the
Thailand Philharmonic Orchestra in 2019. In September 2025, the Thailand Philharmonic announced the appointment of St.Clair as its new music director. St.Clair has served on the faculties of
Southern Illinois University Edwardsville, the University of Michigan, and the University of Southern California. He has worked on the creation and implementation of various symphony education programs, including "Classical Connections", "arts-X–press" and "Class Act". In 2006, he worked with the German
Bundesjugendorchester (National Youth Orchestra). In 2012, St.Clair was appointed principal conductor and artistic leader of the Thornton Symphony Orchestra at the
University of Southern California's
Thornton School of Music. In 2025 St.Clair was recognized as "the longest-tenured American-born conductor of a major American orchestra" for his position with the Pacific Symphony. ==Personal life==