Chaturmas is a period of four months starting from Dev Shayani Ekadashi (Ashadh Shukla Ekadashi) to Prabodhini Ekadashi (Kartik Krishna Shukla Ekadashi). This is the period when god Vishnu goes into yog nidra(sleep). This period is good for devotion, bathing in holy rivers, performing sacrifices, charity, donation and fasting. However, auspicious ceremonies like marriage and other important work are not considered ideal during this period.