
The first two Harry Potter books, Harry Potter and the Philosopher’s Stone and Harry Potter and the Chamber of Secrets, don’t pay much attention to dates and days of the week. For example, Dudley Dursley’s birthday trip to the zoo is said to happen on a Saturday, but June 23, 1991, was actually a Sunday. Similarly, Harry’s birthday, July 31st, is described as falling on a Tuesday, when it was really a Wednesday that year. The third book, Prisoner of Azkaban, makes this issue worse by adding time travel, which puts even more emphasis on dates. One strange example is Buckbeak’s hearing, which is stated to be on April 20th, but careful reading suggests it happened no later than February. J.K. Rowling improved the consistency of dates in Goblet of Fire, making its timeline much more accurate, although this introduced new, different kinds of errors.