I did this trip about 3 years ago in Sep/Oct, just to let you know in one day we had sunshine/rain/snow, it wasn't too cold, we did the trip north to south (going south to north now I believe), and as we left the Yellowstone area the snow came in behind us, so if you go south to north you may hit the snow, it does get cold at night though, especially around the grand canyon area, so be prepared for all types of weather.

Have a great trip

regards,

Martin

his anyone been in october, what's weather like, i've read that it can be cold at altitude, how cold are we talking about?

No, but my plan is to go on the Oct one too, so I'll watch for responses and if I find out from other sources then I'll let you know. Oh, and hello, I'm Allan, 50, and have never been further than Turkey before, so this would/will be a major adventure for me and I can't wait to be there.