Many people assume this is a "hippy" name invented in the 1960s, but it's a lot older than that. There was an extremely popular novel written by
Mary Jane Holmes in 1854 titled "
Tempest and
Sunshine" which is the story of two sisters who are nicknamed
Tempest and
Sunshine because of their contrasting dispositions. The book mentions their birth names are
Julia and
Fanny, but they are mostly referred to by their nicknames in the book. So both
Tempest and
Sunshine are found for a few actual girls in the 19th century, derived from that novel.