In 1994, the UN General Assembly proclaimed 16 September the International Day for the Preservation of the Ozone Layer, commemorating the date of the signing, in 1987, of the Montreal Protocol on Substances that Deplete the Ozone Layer.

15th September celebrated as International Day of Democracy and Engineers' Day of India.

September 8 was declared International Literacy Day by UNESCO on November 17, 1965. Its aim is to highlight the importance of literacy to individuals, communities and societies. Celebrations take place in several countries.

Teachers' Day is celebrated on September 5th in India every year in honor of Dr. Sarvepalli Radhakrishnan, the first Vice-President of independent India and the second President of the country.

International Right to Know Day and World Rabies Day celebrated on September 28.

World Alzheimer’s Day celebrated on September 21.

September 2 has been declared World Coconut Day by the Asian and Pacific Coconut Community (APCC) headquartered at Jakarta, Indonesia, to coincide with APCC’s foundation day.

Hindi Divas (Devanagari: हिन्दी दिवस) is an annual day celebrated on 14 September in Hindi speaking regions of India. Mostly this celebration is a government sponsored event in Central government of India offices, firms, schools and other institutions. It serves to promote and propagate the Hindi language. Its importance is demonstrated by feasts, events, competitions and other services held on this day. The event also serves as a patriotic reminder to Hindi-speaking populations of their common roots and unity.

World Suicide Prevention Day celebrated on September 10.

National Nutrition Week in India is September 1-7.