Thailand's Buddhist calendar gives it a rich cycle of festivals, and several are worth planning a trip around.
Songkran (April 13–15) is the Thai New Year and the most exuberant public holiday of the year. The traditional ritual involves gently pouring water over the hands of elders as a blessing. What this has evolved into on the streets of Bangkok and Chiang Mai is a full-scale multi-day water fight, with water guns, buckets, and pickup trucks mounted with tanks. It's impossible to walk anywhere without getting soaked, which most people find either hilarious or maddening. Chiang Mai's Songkran is particularly famous. Temples hold more solemn ceremonies in the mornings.
Loy Krathong falls on the full moon of the twelfth lunar month — usually November. Thais float small decorated baskets (krathong) made from banana leaves, filled with flowers, a candle, and incense, on rivers, lakes, and canals. The candle carries away bad luck; if it stays lit until you can no longer see the basket, the coming year will be good. Rivers and ponds across Thailand glow with thousands of tiny lights.
Yi Peng coincides with Loy Krathong in northern Thailand. In Chiang Mai, thousands of paper sky lanterns (khom loi) are lit and released simultaneously into the night sky. The sight of them rising over the old city moat is extraordinary. The main mass release is organised and ticketed; smaller launches happen throughout the night across the city.
Makha Bucha (full moon of the third lunar month, usually February) is a major Buddhist holy day marking the occasion when 1,250 monks assembled spontaneously to hear the Buddha preach. Temples hold candlelit processions, and alcohol is officially not sold that day.
Royal Ploughing Ceremony (May, Bangkok) marks the start of the rice-growing season with an ancient Brahmin ritual at Sanam Luang in front of the Grand Palace. Sacred oxen are offered trays of different foods; what they eat supposedly predicts the harvest. One of the few occasions where the ceremonial pageantry of old Siam is still visible.
Vegetarian Festival (October, Phuket) is one of the more intense events on the Thai calendar. Participants of Chinese descent undergo rituals of purification that include, for some devotees, acts of extreme body piercing performed in a state of trance. The streets of Phuket Town fill with processions and firecrackers. Genuinely startling to witness.