Monheit was raised in Oakdale, New York, on Long Island. She began singing professionally while attending Connetquot High School in Bohemia, N.Y., from where she graduated in 1995. As a child, Monheit spent her summers as a student at the Usdan Center For the Creative and Performing Arts, and is a recipient of their distinguished alumna award. As a student at the Manhattan School of Music in New York City, she studied voice under Peter Eldridge. Monheit graduated with honors from the Manhattan School of Music in 1999, earning a BA in music and receiving the William H. Borden Award for outstanding accomplishment in Jazz. As a finalist in the 1998 Thelonious Monk Jazz Institute's vocal competition, she was first runner-up to Teri Thornton. She and her husband, drummer Rick Montalbano Jr., currently reside in New York. They have one child.