Hanuman Jayanti is celebrated in Vaishakh Month in many South Indian regions especially in Andhra Pradesh, Karnataka, and some parts of Tamil Nadu and Kerala. In 2017, Hanuman Jayanti date in Vaishakha month is May 21.
Vaishakha Bahula Dasami (tenth day in second fortnight of Vaishakha masam) is considered as the birthday of Lord Hanuman in these regions. Astrologically, It is believed that after Lord Ram Jayanti (Sri Ram Navami), Goddess Sita Jayanti (Janaki Navami), Hanuman Jayanthi is celebrated. Hanuman was born on Purvabhadra nakshatram.
In other regions, Hanuman Jayanti is celebrated on Chaitra Purnima, during Diwali, and in Margali masam (Margashirsh month).
In 2016, Hanuman Jayanti date in Vaishakha month was May 31.
In 2015, Hanuman Jayanti date in Vaishakha month was May 13.
In 2014, Hanuman Jayanti date in Vaishakha month was May 23.
Hanuman Jayanti 2013 date in Vaishakha month was June 3.
Hanuman Jayanti 2012 date in Vaishakha month was May 15.