Full moons were meant for gathering with the spiritual community, the sangha. These holidays are on full moons with the exception of Bodhi Day, because the Buddha didn't become enlightened on a full moon. As always you can develop rituals and devotional activities on these days and create your own tradition. This is a living and breathing tradition in America where I am, and bringing devotional and rituals from other traditions can be OK if they are done with a Buddhist spirit. Every day is a Buddhist day if you are a Buddhist, but holidays are an excuse to shake things up and do something different.
January 10th -
Mahayana New Year. This day celebrates the altruistic element in the spiritual life, the importance of thinking of others, the giving of the self in the aid of others, and the insight that we are all interconnected and what you do to others, you do to yourself.
February 9th -
Nirvana Day. You could read the 500+ page
The Mahayana Mahaparinirvana Sutra, or you could read for favorite excerpts. This is the day that the Buddha went to
parinirvana. As all holidays, you can chant (puja), gather, rejoice in merit, meditate, and recommit to the spiritual life. This might be a good day to do charnel meditations if you do such a thing. You could imagine what you want people to say at your funeral and plot a course based on that.
Magha Puja is Sangha Day -
March 9th. This day celebrates the spiritual community in it's wide definition and in it's narrow definition. Gathering with others to discuss spirituality should be of optimal importance today. The joys of gathering and friendships are celebrated. A great excuse to get together with spiritual friends. You'd contact your kaliana mitra, your special spiritual friend, on this day, and thank them for their friendship. You can always do a solo puja if you are alone and do metta for all your friends, and everyone, because it's not just friends that help you on your spiritual journey. You could also read the scriptures which were lovingly memorized by the sangha. It is a good day to show respect to the elders that support and carry the tradition. It is traditional to read the
first sermon on this day.
Vesak Day -
May 7th. This day celebrates the birth, and life of the Buddha. Hoist the Buddhist flag, sing song, light incense, do a puja, read the teachings, listen to a teaching by a living teacher. This can be a day to recommit to precepts that you follow. You can put offerings on the shrine at your center or at your home shrine. Doing things for others, bringing joy to others is always a good idea, but if you can think of something like that today, all the better.
June 5th -
Royal Ploughing Ceremony. When the Buddha wondered what to do after he'd explored all the existent traditions but still felt he'd not hit on what he was looking for, he remember back to the day he'd sat off in the trees on the royal ploughing day, and reached a deep state of meditation. He thought to explore that route further and that course correction was what led him to his enlightenment. Thus aside from a Asian farming festival day, this can also be a day when you consider course corrections. It's a kind of easter and rebirth day. The fertility of the spiritual life should be celebrated. You can think about the seeds you wish to plant in your spiritual life and wish to harvest.
July 5th - Dharma Day. You could again read the
Dhammacakkappavattana Sutta: Setting the Wheel of Dhamma in Motion. This is the day you celebrate the teachings that lead to enlightenment.
July 5th: In Sri Lanka, the Buddhism was spread there in the 3rd century by
Mahinda, as written in the
Dipavamsa and
Mahavamsa. This full moon they celebrate the coming of Buddhism to Sri Lanka.
August 3 - Oban Day. This Japanese celebration concerns the ancestors. Maybe a kind of day of the dead, you can reflect on all the important people in your life that are gone. A kind of global day of mourning and celebration. It is also a family reunion holiday opportunity. Gather with your family and let them know how much you love them.
Also called
Hungry Ghosts Day: Chinese: "Intrinsic to the Ghost Month is veneration of the dead, where traditionally the filial piety of descendants extends to their ancestors even after their deaths." And, "...releasing miniature paper boats and lanterns on water, which signifies giving directions to the lost ghosts and spirits of the ancestors and other deities."
December 8th - Bodhi Day. This is a celebration of the Buddha's enlightenment (not on a full moon day). What is enlightenment? How did the Buddha obtain it? Celebrations around this. You can read the
Maha-Saccaka Sutta. The tradition says that the Buddha saw the morning star when he opened his eyes after enlightenment. Consider meditating all night until you see the morning star. I don't know, you could do a silly children's play where Mara is defeated. This is the day Siddhartha became the Buddha. It would be a good day to get a Buddhist name that captures your aspirations.
There need to be September, October and November holidays but I couldn't find any. In America, September is Labor Day, which is back to school for many, end of the harvest. October is Halloween, and November is Thanksgiving. These are lovely and you can inject Buddhism into those holidays. And of course December 25th is Buddhamas, when you celebrate winter solstice by giving presents to young people and loved ones, for people who grew up with the culture of Christmas and Hanukkah, but transform it more in line with your own beliefs. You can light candles along with Hanukkah. You can also celebrate the spiritual teachers of other traditions and eat their birthday cake.
I got to refuge to the Buddha, the Dharma and the Sangha (to the best of my unintegrated abilities). So those three days Vesak, Dharma and Sangha days plus Bodhi Day, I'd say they are the 4 high holidays.
Tibetans will have a lot of other holidays to celebrate Dakinis (Every 25th of each month) and whatnot, such a rich and beautiful tradition. Every tradition will emphasize various things.