The prime reason has been that onam happens to be on September 2, which incidently coincides with Fasting period, Ramzan for Muslims. The Malabar area which vouchsafes for a sizeable number of audience normally experiences a lull during this season. As a result there willl be no major releases from the superstars Mammootty and Mohanlal and also other actors like dileep and Prithviraj.
However there is news that Kalabhavan Mani's Black and White and Jayaram's Kaanakanmani may see the light of the day in Onam. This onam will surely lack lustre and the industry will have to bear the brunt.