Seems that the song was unrelated to Eternal September.
> "Wake Me Up When September Ends" was written by frontman Billie Joe Armstrong about his father, who died from esophageal cancer in September 1982 when Armstrong was 10 years old. Armstrong, at one point, dubbed the song the most autobiographical he had written to that point, considering it "therapeutic" but also difficult to perform.
> "Wake Me Up When September Ends" was written by frontman Billie Joe Armstrong about his father, who died from esophageal cancer in September 1982 when Armstrong was 10 years old. Armstrong, at one point, dubbed the song the most autobiographical he had written to that point, considering it "therapeutic" but also difficult to perform.
https://en.wikipedia.org/wiki/Wake_Me_Up_When_September_Ends