We'll be going for the first time in October too (we usually go during the summer, or in early December).
I'm sure you have to be prepared for both - we've been the week AFTER Thanksgiving for the last three years. The first year, it was rather cold. The second year, it was a mixture - a little cool and a little warm. Last year, mixed again, with rain one of the days.
I'll be checking the weather site as it gets closer. When in October are you going? We'll be there Oct 13-18! Can't wait!!