At the end of September many Green Day fans bombard them with messages to wake up. But why do they do this? Well, simply because of the title of the song. But Billie Joe Armstrong wrote these lyrics for a different reason.
"Wake Me Up When September Ends" was written by Billie Joe Armstrong is about how his fathers passing effected him going from age 10 to 20. On the 10th September 1982 Billie, aged 10, was at his father's funeral and with all the pain that he must have felt at that point he had ran home and locked himself in his bedroom. When his mother came home she told him through his door "Wake me up when September ends." which is where he got the title of the song from.
"Seven years has gone so fast" is one of the first lines in the song. These lyrics tell us that from this point he is speaking about himself at aged 17. In an interview at the Howard Stern Show he spoke about how it took him 7 years to come to terms with his fathers passing as he "avoided writing about him for many years". He continued to say "And then finally having a breakthrough like that felt good." this is probably referring to when he wrote "As my memory rest, But never forget what I lost".
In the song he repeatedly writes "Here comes the rain again, Falling from the stars, Drenched in my pain again, Becoming who we are." Which reminds himself that no matter how old he is, the pain will never leave. However, Billie understands that the pain helped him have a breakthrough which he said "felt good".
"Like my father's come to pass, 20 years has gone so fast" is a line where he talks about his feelings at the time of when he wrote the lyrics in 2004. He tells us that he feels that time has passed so quickly. Which he then ends the song by repeating the lyrics "Wake Me Up When September Ends". These lyrics are important in telling us that he truly feels like time has passed so quickly as he still hears his mother saying those words to him all these years later and those words will stick with him for the rest of his life remembering his father each September.