Sometimes Disney will offer special "Fall discounts," and those discounts will cover certain weeks in October, November and early December. There is usually some sort of Fall hotel offer for AP holders, and some sort of Fall offer for the general public (the former's discount is slightly greater than the latter's).
However, over the last couple of years the Fall discounts have covered fewer dates than they used to cover in the past. They used to include a wider range of weeks in the 3 months I mentioned. Now, the discounts often skip weeks or days when Disney is expecting large crowds. When they expect large crowds over a certain period of time, they don't need to offer any discounts. Also, some dates may show up as unavailable for the discount at first, and then open up much later on.
It is worth mentioning that there were no Fall discounts during the year that Cars Land and Buena Vista Street opened in DCA (2012). That was likely due to Disney assuming that they would be very busy all year, and therefore would not need to offer hotel savings. The discounts resumed in 2013.
At this point in time, I am almost inclined to think that this could be another year like 2012. It is possible that there might not be any Fall discounts this year, due to the ongoing Diamond Celebration (which is lasting at least through the end of 2015, and probably beyond). Disney may once again assume that the crowds will be pretty substantial for the next 7 months and not extend any discounts.
IF there is going to be a Fall discount of any kind this year, we probably won't know about it until early September.