In Saudi Arabia, Ramadan First day in 1438 Hijri will be Saturday, 27th May 2017,InshaALLAH. Ramadan 2017 is expected to be 29 day long because of slight chances of Shawal moon visibility in 24th June 2017. Otherwise 25 will be the last day of Ramadan in Saudi Arabia. As per Umm al-Qura Calendar and moon crescent visibility on 26th May evening possible by optical aid and naked eye if weather remains clean. Dates may also change, so it is requested to wait till official announcements.
Saudi Arabia's Umm al-Qura calendar has a good rule. Since the beginning of AH 1423 (16 March 2002), the rule has been clarified a little by requiring the geocentric conjunction of the sun and moon to occur before sunset, in addition to requiring moonset to occur after sunset at Mecca.
This ensures that the moon has moved past the sun by sunset, even though the sky may still be too bright immediately before moonset to actually see the crescent.
In 2007, the Islamic Society of North America, the Fiqh Council of North America and the European Council for Fatwa and Research announced that they will henceforth use a calendar based on calculations using the same parameters as the Umm al-Qura calendar to determine (well in advance) the beginning of all lunar months (and therefore the days associated with all religious observances). This was intended as a first step on the way to unify, at some future time, Muslims' calendars throughout the world.
