The Parsi New Year, Navroz is traditionally celebrated on the spring equinox day.
Parsi Calendars – Shasenshahi and Kadmi
A group of Parsis migrated to India to escape persecution in Persia. When they came and settled in west coast of India, they also brought their calendar, Shahenshahi and Kadmi.
Navroz and Pateti observed on same day
The migrant Parsi community for some reason did not take into account the leap year which occurs once in four years and the precession of equinox of 1 day which occurs in 72 years. Because of this, the Parsi New Year Navroz and Pateti Observance day has come to be celebrated on the same day only among Indian Parsis.
The celebration of Pateti has got a noble thought in it. Let us all on this occasion, being Parsi or not, observe and genuinely repent for our misdeeds, harsh words, so that we move forward with all members of this world happily. Let us use this day, this occasion to renew our friendships and move forward as this world is one happy family.