Hanuman Jayanti is celebrated on the full moon day of Chaitra month to commemorate the birth of Vanara God Hanuman. Hanuman, also known as Anjaneya, was a keen devotee of Lord Rama and Sita.
Depending on the regional beliefs and also the type of calendar being followed, devotees celebrate Hanuman Jayanti during different times of the year. Hanuman Jayanti observed during Chaitra Purnima is the most popular one in North India.
In Andhra Pradesh, Hanuman Jayanthi is a 41-day celebration, which begins on Chaitra Purnima and ends on the tenth day of Krishna Paksha in Vaishakha month. The devotees observe 41 days Deeksha during this festival period.
In Tamil Nadu, Hanuman Jayanti is also known as Hanumath Jayanthi and is celebrated during Margashirsha Amavasya, which, as per Gregorian calendar, falls in December or January.
Hanuman Jayanti celebration in Karnataka is popularly known as Hanuman Vratam and is observed on Shukla Paksha Trayodashi in Margashirsha month.
Hanuman was believed to be born at Sunrise and hence spiritual discourses on temples start before Sunrise and stop after Sunrise on Hanuman Jayanti day.