Almanacs differ this year†. On Tuesday, 22 March 2016 Bhadra (Vishti karana) covers the whole evening and lasts until 4:20 am on 23 Mar, past the middle of the night. This page shows the day whose pradosh holds the tithi. Many almanacs, including the large online ones, take the evening of Wednesday, 23 March 2016 instead, although the tithi ends at 5:30 pm on 23 Mar that day; some take the tail of Bhadra (Bhadra Punchha) that night, which is not worked out here. Our faculty is reviewing this rule. Holi follows that day, so it moves with it.
2016
Wednesday, 23 March 2016
In 2016 the tithi runs from 3:12 pm on 22 Mar to 5:30 pm on 23 Mar; it is running at pradosh, the twilight just after sunset on Tuesday, 22 March 2016, so that is the reference day, and Holi is on Wednesday, 23 March 2016.
2017
Monday, 13 March 2017
In 2017 the tithi runs from 8:23 pm on 11 Mar to 8:23 pm on 12 Mar; it is running at pradosh, the twilight just after sunset on Sunday, 12 March 2017, so that is the reference day, and Holi is on Monday, 13 March 2017.
How the date is fixed
The reference day falls on the full-moon day (Purnima) of the lunar month Phalguna. The date is the day on which that tithi is running at pradosh, the twilight just after sunset. Bhadra (Vishti karana) is avoided. When Bhadra covers the whole evening and lasts past the middle of the night, almanacs differ on the day; this page still shows the day whose pradosh holds the tithi†. Holi itself is kept 1 day after that day.
† Practice varies between schools; our faculty is reviewing these rules.
About
Holi is anchored to Phalguna Purnima, the full moon that ends the lunar year in amanta reckoning. The bonfire is lit on the Purnima evening and the play of colours, called Dhulandi or Rangwali Holi, takes place the next morning, which in amanta terms is already Chaitra Krishna Pratipada. The site therefore lists Holi on the day after Holika Dahan, whatever the tithi at sunrise, so the two always stay one day apart. In Braj the celebrations begin a week earlier with Lathmar Holi, and in Bengal the same day is Dol Purnima.
How it is observed
Colours and water are played with in the morning, followed by visits to family and sweets such as gujiya.