Rain was born in Winnipeg, Manitoba. He studied acting at the Banff School of Fine Arts in Banff, Alberta and the Bristol Old Vic Theatre School in Bristol, England. As a stage actor, his association with the Stratford Festival of Canada spans more than four decades. He has performed in a wide variety of theatrical roles, most notably in a Stratford, Ontario production of Henry V, which was adapted for television in 1966. In 1972, Rain was nominated for the Tony Award for Best Supporting or Featured Actor (Dramatic) for his performance in Vivat! Vivat Regina!