"Wake Me Up When September Ends" is a song by American rock band Green Day. It was released in June 2005 as the fourth single from their seventh album, American Idiot.
The song deals with the death of lead singer Billie Joe Armstrong's father, who died when Armstrong was a child.
The single peaked at number six in the United States, becoming Green Day's third Top 10 single. It also peaked at #8 in Canada and the UK, while making #13 in Australia. "Wake Me Up When September Ends" had sold 1,652,000 copies as of May 2010, and was the second highest selling single in the U.S. from American Idiot, behind only the multi-platinum "Boulevard of Broken Dreams". The song ended the streak of Green Day's three consecutive #1 hits on the Modern Rock Tracks chart ("American Idiot", "Boulevard of Broken Dreams" and "Holiday"), but it hit #2 on the chart almost hitting #1 by Gorillaz "Feel Good Inc.". The song also hit #2 on the Adult Top 40 and #4 on the Mainstream Top 40. This was the band's most successful song to the adult contemporary market, hitting #13 on its own chart and their only song to chart other than "Boulevard of Broken Dreams". The song is certified Silver in the United Kingdom for sales of 200,000 
Like the majority of the videos from the album American Idiot, it was directed by Samuel Bayer. The video features Green Day's support guitarist, Jason White. This is the second time Jason White has appeared in a Green Day video, first appearing in "When I Come Around", ten years earlier but not as a band member.
The video focuses on a very loving couple (played by Jamie Bell and Evan Rachel Wood). The boyfriend promises never to leave his girlfriend but they later argue when the boyfriend enlists in the United States Marine Corps. The boyfriend interprets his actions as a way to show her that he loves her so much that he would put his life on the line to keep her safe; the girlfriend, however, is heartbroken, as he broke his vow to never leave her, and terrified at the thought that he might die in battle. The video then shows the boyfriend in battle in Iraq being ambushed by insurgents. This scene is intercut with scenes of the girlfriend tearfully mourning in a quiet field. The video ends on this juxtaposition, emphasizing the pain and heartache of losing loved ones due to the war.
This video adds to the American Idiot anti-war sentiment of the Iraq War. The song eventually became a tribute song to the victims of Hurricane Katrina, and sound bites were added from various news coverages to the song. A live version of the song, recorded on September 3, 2005, at Gillette Stadium in Foxborough, Massachusetts was released soon after and dedicated to the hurricane's victims. The song was performed live with U2 guitarist The Edge in the pregame show of the Monday Night Football game between the New Orleans Saints and the Atlanta Falcons; it was the first game played in the Superdome in New Orleans after Hurricane Katrina.