The Ambubachi Mela is the most important festival of Kamakhya temple celebrated in the month of June 3rd week (Ahaar month in Assamese). The Ambubachi Mela is unique with its own significance. It is believed that the presiding goddess of the temple, Devi Kamakhya, the Mother Shakti, goes through her annual cycle of menstruation during this time stretch.

Ambubachi Mela is held at the Kamakhya temple, after being closed for the afore-mentioned three days. The goddess Kamakhya is given a bath and purified on the fourth day. The temple reopens on the fourth day and the devotees are allowed to enter inside the temple for worship. Thousands of devotees from all over the country and abroad visit this Ambubachi Mela.

It is believed that mother earth becomes unclean for three days like the traditional women's menstrual seclusion. During these three days some restrictions are observed by the devotees like not cooking, not performing puja or reading holy books, no farming etc.

The festival is held every year to commemorate the yearly menstruation of Goddess Kamakhya. It is also said that during the month of mid-June, which is also an Ahar, there is a natural spring which flows through the yoni.

During Ambubachi, it’s important to allow Mother to rest. Every day we are asking Her for things, so on this day we serve Her rather than asking Her to serve us. In the United States, this concept is similar to Mother’s Day, when we pamper our mothers in some way to let them know how much we love and appreciate them.

Ambubachi can be difficult to place on the calendar if you’re not familiar with calculating the North Indian calendar, as it does not reliably align with common lunar events such as amavasya or purnima. It is generally celebrated close to the summer solstice on the seventh day of the month of Ashadha (Ashara in Assam), which typically falls on June 21 or 22 and ends around June 25 or 26.