“Wake Me Up When September Ends” is a song by American rock band Green Day, released on June 13, 2005, as the fourth single from the group’s seventh studio album, American Idiot (2004).

The acoustic ballad was written by frontman Billie Joe Armstrong about the death of his father when he was 10 years old.

The song became a hit single, peaking at number six on the US Billboard Hot 100. It was also a top-10 single in the United Kingdom, Belgium, and New Zealand and was a number-one single in the Czech Republic. In the United States, the song became symbolic after Hurricane Katrina, where it was dedicated to victims of the disaster, and also regarded as a dedication to the victims of the September 11 attacks that occurred in 2001. The song was certified platinum by the Recording Industry Association of America.