Jewish holiday of Rosh Chodesh Iyyar, begins at sundown on 11-Apr-2021 and ends at. Iyar is the second month on the Jewish calendar counting from Nisan. A Reading and Activity for Rosh Chodesh Iyar. When we reached Mara on Rosh Chodesh Iyar (which incidentally fell out on Shabbos the year of the Exodus), we were ready to hear the King's word. That place was given its name, which means “bitter,” by the fact that the water there was, in fact, quite bitter, and not drinkable.