Chaturmas Vratais the observance that is performed for four holy months as per Hinduism. Chatur Mas Vratam begins either in Ashada masam on Ekadasi or Dwadashi or on Pournami day when Sun enters into Karka (Cancer) rashi. According to major Panchangas, in 2015, the date of Chaturmasa Vratam Arambh is on July 15 / July 16 / July 19. Ashada Shudda Dwadashi is also observed as Vasudeva Dwadashi.
Some more people observe Chatur Mas Vrata from Sayani Ekadasi or Deva Shayana Ekadashi, which falls on July 15 in 2016.
According to Puranas, in these Chaturmas, four holy months – Shravana, Badrapada, Aswayuja, Kartika, Lord Vishnu stays at Paathala with King Maha Bali. During Chatur Mas vrata, people of Shaiva sects observe Shiva Shayanotsavam and Shiva Dolotsavam. They believe that during these four holy months Lord Shiva goes into Yoganidra (meditative sleep) just like Lord Vishnu.
Chaturmas Vrata in Previous Years
According to major Panchangas, in 2014, the date of Chaturmasa Vratam Arambh is on July 8 / July 9 / July 12.
According to major Panchangas, in 2013, the date of Chaturmasa Vratam Arambh is on July 19 / July 20 / July 22.
According to major Panchangas, in 2012, the date of Chaturmasa Vratam Arambh was on June 30 / July 1 / July 3.