The best time to visit Bodh Gaya is from October to March, when the Bihar heat is manageable and the pilgrimage season is at its peak. December and January in particular see enormous numbers of Tibetan pilgrims and lamas arriving for teachings and winter retreats — the atmosphere around the Mahabodhi Temple is extraordinary during this period, with thousands of maroon-robed monks and laypeople filling the grounds at dawn.
April and May are brutally hot in the Bihar plains, with temperatures regularly exceeding 40°C. The monsoon arrives in June and brings relief from the heat but makes getting around Bihar difficult; some of the international monasteries scale back their activities during the summer months.
The Buddhist pilgrimage year has its own calendar. The full moon of Vaisakha (April–May) marks Buddha Purnima, the anniversary of the Buddha's birth, enlightenment, and death — the holiest day in Theravada Buddhism, when Bodh Gaya fills with pilgrims from across Asia. Losar, the Tibetan New Year (usually February), brings a large influx of Himalayan Buddhists.