In September 2023, the following holidays and observances are celebrated:
- Labor Day (September 4, Monday): A federal holiday in the United States, honoring the American labor movement and the contributions of laborers to the countrys development.
- West Indian Day Parade (September 4, Monday): A vibrant celebration of Caribbean culture held in Brooklyn, New York, as part of the Labor Day festivities.
- International Day of Charity (September 5, Tuesday): A day to promote and support charitable efforts worldwide.
- National Cheese Pizza Day (September 5, Tuesday): A day to enjoy and appreciate this popular pizza variety.
- International Literacy Day (September 8, Friday): A day to raise awareness about the importance of literacy and education.
- Star Trek Day (September 8, Friday): A celebration of the popular science fiction franchise, marking the anniversary of the original series' first airing in 1966.
- Selichot (September 9, Saturday): A Jewish observance of penitential prayers and liturgy leading up to the High Holy Days.
- Grandparents Day (September 10, Sunday): A day to honor and appreciate grandparents and their contributions to families and society.
- World Suicide Prevention Day (September 10, Sunday): A day to raise awareness about suicide prevention and promote mental health support.
- Patriot Day (September 11, Monday): A day of remembrance for the victims of the September 11, 2001, terrorist attacks in the United States.
- International Day of Democracy (September 15, Friday): A day to promote and uphold the principles of democracy worldwide.
- Batman Day (September 16, Saturday): A celebration of the iconic comic book superhero, first introduced in 1939.
- Oktoberfest (Start) (September 16, Saturday): The beginning of the world-famous German beer festival, which typically runs for 16-18 days.
- Constitution Day (September 17, Sunday): A day to commemorate the signing of the United States Constitution in 1787.
- International Talk Like a Pirate Day (September 19, Tuesday): A fun and lighthearted observance where people are encouraged to speak like pirates.
- National Voter Registration Day (September 19, Tuesday): A day to promote voter registration and participation in the democratic process.
- National Pepperoni Pizza Day (September 20, Wednesday): A day to enjoy and celebrate this popular pizza topping.
- Saint Matthew (September 21, Thursday): A Christian feast day honoring the apostle and evangelist Matthew.
- International Day of Peace (September 21, Thursday): A day to promote peace and non-violence worldwide.
- Rosh Hashanah (Start) (September 22, Friday): The Jewish New Year, marking the beginning of the High Holy Days.
- MIA Recognition Day (September 22, Friday): A day to honor and remember the sacrifices of missing in action (MIA) service members.
- International Day for the Preservation of the Ozone Layer (September 22, Friday): A day to raise awareness about the importance of protecting the Earth's ozone layer.
- Emmy Awards (September 25, Monday): An annual awards ceremony honoring excellence in the television industry.
- National Cheeseburger Day (September 25, Monday): A day to enjoy and celebrate this classic American dish.
- International Day of Awareness of Food Loss and Waste (September 29, Friday): A day to raise awareness about the global issue of food loss and waste.
- International Food Loss and Waste Awareness Day (September 29, Friday): A day to promote solutions for reducing food loss and waste.
- National Starbucks Day (September 29, Friday): A day to celebrate the popular coffee chain and its impact on global coffee culture.
- International Translation Day (September 30, Saturday): A day to recognize the important role of translators in fostering understanding and communication between languages and cultures.
- World Maritime Day (September 30, Saturday): A day to raise awareness about the importance of shipping and maritime industries for global trade and development.
- National Day for Truth and Reconciliation (September 30, Saturday): A Canadian holiday to honor the survivors of residential schools and promote reconciliation between Indigenous and non-Indigenous peoples.
