Although I have not been in October, I would strongly recommend staying away from September, especially with a little one. We went once during the last week of September and it was HOT, like walking on the surface of the sun hot. Showering twice a day, pouring sweat just from blinking hot. I am used to heat in the summer, typically in my hometown it is about 90 in the summer. The coolest day that week was 95, most days were over 100. It wasn't a busy time but I didn't want anyone within a 100 foot radius of me. We had a fantastic trip but we were all a little extra grumpy from the heat. I don't know how people do it that go in the summer. I couldn't handle it at all.
(I know, big help) The only days that are higher than a 5 on all crowd calendars are Epcot on the weekends, but I expected that. For me, a level 5 and under is perfect! And if it's 6 or 7, so be it, I've got my fast passes and then I don't mind waiting 20-30 minutes for a ride. I've also been told that if I didn't think the first two weeks of June were crowded (I didn't, thought crowd levels were great then), then October should be no problem. Sooo, don't expect all walk-ons, but don't expect shoulder to shoulder crowds either. A happy medium.
(avoiding Epcot food/wine on weekends)
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This is the very week we are going...booked originally based on research on crowd levels and weather (heat and precipitation). From what I now hear, it's busier than it used to be...and am just learning of US fall breaks. But what you say here makes total sense. And if you want to hit the Electrical Parade or stay later than 7pm without attending the party, then non-party days would be busier.