I asked my friend that same question, and October he says is pretty darn cool, and cold at night. That's one of the reasons that I am doing the northern routes around now. Hope to be heading south late September. Part of me wants to witness the changing of the leaves, which I hear is spectacular in October, but I get cold easily, so I'm not sure if I want to be there that late. Guess it depends on whether or not I find a better sleeping bag, mine is supposed to be a -20 bag, but I get cold in it when it's 50! LOL. I think it's just way too big for me, so too much dead air in there that doesn't warm up.