Ram Navami in 2016 was observed on Friday, 15th April. Rama Navami in 2017 is on 5th April, Wednesday. As per Hindu calendar, Ram Navami is celebrated on the ninth day (navmi) of Chaitra month (lunar calendar).
The dates of Ram Navami differ every year because of the fact that it is based on Hindu calendar and Hindu calendars are based on the Solar and Lunar cycles. It is one of India's most jubilant and fun-filled festival which publicize the message of happiness and victory of good over evil.
Lord Rama was born on Navami Tithi during Shukla Paksha of Chaitra month. Each year this day is celebrated as the birthday of Lord Rama. Lord Rama was born during Madhyahna period which is middle of Hindu day. Madhyahna which prevails for six Ghatis (approximately 2 hours and 24 minutes) is the most favorable time to perform Rama Navami Puja rituals. The mid-point of Madhyahna marks the period when Shri Rama was born and temples exemplify this moment as the birth moment of Lord Rama. The reciting of Shri Rama and celebration reaches its top during this time.
Due to the vast use of the western clock and Gregorian calendar people assume 12 p.m. as Madhyahna moment. This could have been correct if sunrise and sunset occur exactly at 6 a.m. and 6 p.m. respectively but at most places sunrise and sunset timings are different from six O'clock. Hence, the exact time to celebrate the birthday of Lord Rama falls between 11 a.m. and 1 p.m. for most Indian cities. Hindu midday period for all cities and this time should be used to mark the birth of Shri Rama.
Eight Prahar fasting is suggested during Rama Navami. Which means devotees should observe the fast from sunrise to sunrise. Rama Navami Vrat can be observed in three different ways, casual Nemittik-which can be observed without any cause, the continuation which can be observed throughout life without any wish and desirable (kamya) - which can be observed to fulfill any wish.