Chaturmas is a spiritual period of four months and this is the good time to minimize the quantity of our sense gratification through meditation and other spiritual activities. Chaturmas is reserved for penance, austerities, religious observances, recital of mantras, bathing in holy rivers, performing sacrifices, and charity are prescribed. Devotees resolve to observe some form of vow, be it of silence or abstaining from a favourite food item, or having only a single meal a day. Fasts and purity during this holy period help maintain health, for which there is likely a scientific rationale, disease spreading more readily with the onset of monsoon.
Chaturmas begins on Shayani Ekadashi, the eleventh day of the bright half, Shukla paksha, of Ashadh until Prabodhini Ekadashi, the eleventh day of the bright half of Kartik (fourth month to eighth month of the Hindu lunar calendar) in Hinduism. One should perform spiritual activities in these four months as much as possible. And every auspicious and spiritual activity becomes more fruitful in these four months.
During Chaturmas, it is believe that Lord Vishnu who protects the universe goes into a deep state of meditation (Yoga Nidra) for four months called Chaturmas. It is also believe that other Devas are at rest during this period and should not be disturb. And therefore during this period, Lord Shiva takes care of the Universe. Therefore, the Chaturmas commences with a month of ‘Sawaan’ dedicated to Lord Shiva. This period corresponds with the rainy season in India and no auspicious events are organise during this period.
The Chaturmas culminate with the end of Lord Vishnu’s Yoga Nidra. In some traditions, Chaturmas ends with the Tulsi Vivah, i.e. Dwadashi Tithi of Kartik Shukla Paksha. And with Tulsi Vivah, the season of weddings in the Hindu community begins.
Chaturmas has significance for Jains and Buddhists as well. Gautama Buddha stayed at the royal garden of King Bimbisara of Rajgir. Whom he had recently converted, for period of Chaturmas and gave sermons. This practice is followed by monks to this day. Another reason for ascetics to stay in one place during the rainy season is the tropical climate. That produces a large number of insects, which would be trample by travelling monks.