Iran Air

As in all the Moslem Countries, also in Iran the calendar starts the calculation of the years from the Egira (622 AD), from when that is the prophet Mohammed from the Mecca migrated to Medina. But in Iran it is a solar calendar while in the Arabic Countries it is lunar. Then the base is equal but it changes the calculation of the years.
the Iranian year begins on March 21, first day in spring, with the feast of the Nowruz, the most important of the whole year.
The first six months have 31 days, the five followings have 30, while the last, the twelfth one, has 29 (or 30 in the leap years). 1) Farvardin: (31 days), from on March 21 to April 20
2) Ordibehesht: (31 days), from on April 21 to May 21
3) Khordad: (31 days), from on May 22 to June 21
4) Tir: (31 days), from on June 22 to July 22
5) Mordad: (31 days), from on July 23 to August 22
6) Shahrivar: (31 days), from on August 23 to September 22
7) Mehr: (30 days), from on September 23 to October 22
8) Aban: (30 giomis), from on October 23 to November 21
9) Azar: (30 days), from on November 22 to December 21
10) Dey: (30 days), from on December 22 to January 20
11) Bahman: (30 days), from on January 21 to February 19
12) Esfand: (29/30 days), from on February 20 to March 20 The Islamic calendar in the Arabic Countries is tightly lunar. Year consists of twelve alternate months of 30 or 29 days but the last month in a few years can be also of 30 days. Therefore the year can last 354 or 355 days. So in the Moslem calendar, in comparison to the Iranian calendar or to that western, every year begins 10, 11 or 12 days before.
The Moslem months are:
1) Moharram (The month of Imam Hossein martyrdom)
2) Safar
3) Rabi-ol Avval
4) Rabiossani
5) Jamadi-ol Avval
6) Jamadiossani
7) Rajab
8) Shaban
9) Ramadan or Ramazan (the month of the fast)
10) Sbaval
11) Zighadeh
12) Zihajjeh (the month of the ceremonies to the Mecca)
  The religious celebrations follow the variations of the lunar calendar, while the national festivities are fixed with the solar calendar.
  The numbers