The major events celebrated every year are:
Vesakha Puja: or the Buddha Day is the major Buddhist festival of the year as it celebrates the birth of Prince Siddharta, the enlightenment and parinibbana of The Buddha on that same day. It is celebrated on the first full Moon day in May, except in a leap year when the festival is held in June. This celebration is called Vesakha being the name of the month in the Indian calendar.
Magha Puja: or Sangha Day takes place on the full moon day of the third lunar month. This holiday is observed to commemorate an important event in the life of The Buddha. This event occurred early in the Buddha’s teaching life. After the first Rains Retreat (Vassa) at the Deer Park at Sarnath, the Buddha went to Rajagaha city where 1250 Arahats,(Enlightened saints) who were the Buddha’s disciples, without prior appointment, returned from their wanderings to pay respect to the Buddha. They assembled in the Veruvana Monastery with the two chief disciples of the Buddha, Ven. Sariputta and Ven. Moggalana.
The assembly is called the Fourfold Assembly because it consisted of four factors: (1) All 1250 were Arahants; (2) All of them were ordained by the Buddha himself; (3) They assembled by themselves without any prior call; (4) It was the full moon day of Magha month (March).
Chinese New Year,
Asadha Puja: or Dhamma Day means to pay homage to the Buddha on the full moon day of the 8th lunar month (approximately July). It commemorates the Buddha’s first teaching: the turning of the wheel of the Dhamma (Dhammacakkappavattana Sutta) to the five ascetics at the Deer Park (Sarnath) near Benares city, India. Where Kondanna, the senior ascetic attained the first level of enlightenment (the Sotapanna level of mind purity).
Kathina Ceremony (Robe offering ceremony)
Is held on any convenient date within one month of the conclusion of the Vassa Retreat, which is the three month rains retreat season (Vassa) for the monastic order. It is the time of the year when new robes and other requisites may be offered by the laity to the monks.
[8:54 PM, 12/29/2020] Lili Siswanto: Ulambana (Ancestor Day)
Is celebrated throughout the Mahayana tradition from the first to the fifteenth days of the eighth lunar month. It is believed that the gates of Hell are opened on the first day and the ghosts may visit the world for fifteen days. Food offerings are made during this time to relieve the sufferings of these ghosts. On the fifteenth day, Ulambana or Ancestor Day, people visit cemeteries to make offerings to the departed ancestors. Many Theravadins from Cambodia, Laos and Thailand also observe this festival.
Ulambana is also a Japanese Buddhist festival known as Obon, beginning on the thirteenth of July and lasting for three days, which celebrates the reunion of family ancestors with the living.