September 31 is not a valid calendar date, so there is no official national day on September 31 in any country.

Why September 31 doesn’t exist

  • September has only 30 days in the standard Gregorian calendar, so September 31 is not a real date anywhere.
  • Any reference to “September 31 National Day” is either a mistake , a made‑up meme , or a confusion with another day such as September 30 (e.g., Canada’s National Day for Truth and Reconciliation / Orange Shirt Day).

Common nearby dates people mix up

  • September 30 – National Day for Truth and Reconciliation (Canada), observed federally to honor survivors of residential schools and promote reconciliation.
  • Early September – U.S. Labor Day on the first Monday of September , which sometimes bleeds into people misremembering dates around the end of the month.

In short, there is no legitimate “September 31 National Day” ; the date itself does not exist in the calendar.

Information gathered from public forums or data available on the internet and portrayed here.