Vassa (Pali: vassa-, Sanskrit: varṣa-, both “rain”) is the three-month annual retreat observed by Theravada practitioners. Taking place during the wet season, Vassa lasts for three lunar months, usually from July to October.
For the duration of Vassa, monastics: senior and junior monks should remain in one place, typically a monasteries or temple grounds. In some monasteries, monks dedicate the Vassa to intensive meditation. Some Buddhist lay people choose to observe Vassa by adopting more ascetic practices, such as giving up meat, alcohol, or smoking. The number of years a monk has spent in monastic life is expressed by counting the number of vassas he has observed according to Vassa’s terminology.
Vassa begins on the first day of the waning moon of the eighth lunar month, which is the day after Asalha Puja or Asalha Uposatha (“Dhamma day”). It ends on Pavarana, when all monastics come before the sangha and atone for any offense that might have been committed during Vassa.
Vassa is followed by Kathina, a festival in which the laity expresses gratitude to monks. Lay Buddhists bring donations to temples, especially new robes for the monks.
The Vassa tradition predates the time of Gautama Buddha. It was a long-standing custom for mendicant ascetics in India not to travel during the rainy season as they may unintentionally harm crops, insects or even themselves during their travels. Many Buddhist ascetics live in regions which lack a rainy season.Consequently, there are places where Vassa may not be typically observed.
The 2016 date for Vassa is July 20 – October 16.