About the Umm al-Qura calendar
Umm al-Qura is the official Hijri calendar of Saudi Arabia, used for government transactions and contracts. It is based on astronomical calculation, so the start of a month can differ by a day from moon sighting, especially for Ramadan and Eid.
Hijri months
Muharram, Safar, Rabi al-Awwal, Rabi al-Thani, Jumada al-Ula, Jumada al-Akhirah, Rajab, Shaban, Ramadan, Shawwal, Dhu al-Qadah, Dhu al-Hijjah.