13 January is the 13th day of the year. There are 352 days until the end of the year (353 in leap years).
Notes and references
- ↑ Harry Potter and the Prisoner of Azkaban, Chapter 12 (The Patronus) "Eat the lot, or Madam Pomfrey will be after my blood. Same time next week?' 'OK,' said Harry". It was determined they had the first lesson shortly after the new term started in early January, meaning their next lesson was around this time