When Is Rosh Chodesh Adar 2 2025. During a jewish leap year, the holiday of purim, which takes place on the 14th. The 1st day being the 30th of shevat and the 2nd day of rosh chodesh being the 1st of adar.
That added month is a second adar, and jewish leap years contain an adar i and an adar ii, called adar alef (ืืืจ ื) and adar beit (ืืืจ ื). The rule is that rosh chodesh will always be the next day in the week than the previous.