2017
Tuesday, 4 April 2017
In 2017 the tithi runs from 11:20 am on 4 Apr to 10:04 am on 5 Apr; it is running at aparahna, the afternoon on Tuesday, 4 April 2017, so that is the day of Ram Navami.
2018
Sunday, 25 March 2018
In 2018 the tithi runs from 8:02 am on 25 Mar to 5:54 am on 26 Mar; it is running at aparahna, the afternoon on Sunday, 25 March 2018, so that is the day of Ram Navami.
How the date is fixed
Ram Navami falls on the ninth day of the bright half of the lunar month Chaitra (Shukla Navami). The date is the day on which that tithi is running at aparahna, the afternoon.
About
Ram Navami falls on the ninth tithi of the bright half of Chaitra and closes Chaitra Navratri. The Ramayana places the birth at midday in Punarvasu nakshatra, so the madhyahna (midday) period is the governing moment, and the day whose midday holds Navami is chosen. Where Navami touches midday on two days, the texts prefer the day on which Navami is joined with Punarvasu or, failing that, the first day. Ayodhya, Bhadrachalam and Rameswaram hold their largest gatherings of the year on this day.
How it is observed
Recitation of the Ramayana, a midday birth ceremony in temples and a fast kept until the midday puja.