This is the name of one of the main adult female characters in Catherynne M. Valente's adult fantasy novel "Palimpsest" (2009). In the novel November remembers having read a book called "The Girl Who Circumnavigated Fairyland in a Ship of Her Own Making" when she was a child, and the heroine of that book was called September. Valente later wrote that book as a crowd-funded work. It became the first volume in her bestselling "Fairyland" series.
This name was very popular in the English-speaking world at the end of the 19th century. Though it declined in use over the next 100 years, it staged a successful comeback at the end of the 20th century. The American sitcom Will and Grace (1998-2006) may have helped, though the name was already strongly rising when it premiered. It was the top name for girls in England and Wales in 2006.