If the leaves have turned it's only because its already been cold, and would be colder when you arrive, that combined with a little cold rain can put a real dampener on the rally. It's mid July now and the weather has been great for riding in the mountains, Temps have gotten into the 90's but cooler at higher elevations, and if it rains, no big deal. Here many of the trees have shed their leaves before the rest of them change color because of the more gradual temperature change. For magnificent fall colors visit Maine where winter comes on fast and all the leaves change at the same time. Lets not get hung up on the leaf thing, I opt for warm and green. I will be there no matter the date, but given the option choose better weather for all.