30 October is the 303rd day of the year (304th in leap years). There are 62 days remaining until the end of the year.
- 1492: Nicholas de Mimsy-Porpington meets Lady Grieve. He tries to straighten her teeth, but causes her to grow a tusk instead, and is executed for it the following day.
- 1949: Molly Prewett is born to Mr. and Mrs. Prewett.
- 1991: The Gryffindor first-year students have an Astronomy Class at midnight, on the top of the Astronomy Tower.
- 1994: The delegations from the Beauxbatons Academy of Magic and the Durmstrang Institute arrive at Hogwarts School of Witchcraft and Wizardry in preparation for the Triwizard Tournament.