Islamic holidays are determined by lunar sightings but, whereas some Muslim countries use information derived from observatories, unaided observations are preferred in Qatar, which makes exact dates difficult to predict, as the moon may be obscured by cloud, for example. There’s also a complicated conversion to be made from the Islamic to the Gregorian calendar. The dates shown below are therefore approximate, and the only way to be sure that a holiday has begun is to hear the gun that’s traditionally fired on such occasions, to hear an announcement on the local radio or to wake to hear less than usual traffic noise!