12 September is the 255th day of the year (256th in leap years). There are 110 days remaining.
- 1991: The first Flying lesson of the year takes place at half past three p.m.; Neville Longbottom breaks his wrist after a dreadful flight. Harry Potter is made Seeker of Gryffindor after he chases Draco Malfoy. Draco Malfoy challenges Harry to a duel at midnight. When Harry, Ron, Hermione, and Neville get to the Trophy Room for the midnight duel, they discover Draco told Argus Filch, the caretaker, that they would be out of bed at that time. The group manages to avoid Filch, but have a run in with Fluffy instead.
- 1996: Hannah Abbott had been taken out of Herbology to be told her mother had been found dead.