The Vassa tradition predates the time of Gautama Buddha.[1] 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.[4] Many Buddhist ascetics live in regions which lack a rainy season.[7] Consequently, there are places where Vassa may not be typically observed.[7]
The 2016 date for Vassa is July 20 - October 16.[9]