I'd like to plan a roadtrip through some of following the states: Nevada, Arizona, New Mexico, Colorado, Utah and Wyoming.

I was thinking of going in mid-September. I imagine it will still be (very?) hot in Nevada, Arizona and New Mexico; a little cooler further north.

I'm wondering how is mid-September in those parts? Is there a low season for travel in the region?

Low season, if they really have one anymore would be after fall color season and before winter sets in. Have been in Utah in late October and the daytime temps have still been in the 80's with nights going down into upper 40's-50's. If you are going to visit a number of national parks get an America the Beautiful pass at your first stop. Costs $80. Is good for entrance fees for a calendar year at any federal area that charges entrance fees. Most of the larger parks are now $25 each.

What part of New Mexico? Albuquerque and points north are cooler than the south.

Lee Ann

I used to go to camp in Ute Park, New Mexico. That is a beautiful part of New Mexico. It is between Eagles Nest and Cimarron.

You can check out my road trip reports fpr Arizona and Wyoming (touching Colorado and South Dakota) any maybe pick up some useful pointers on http://members.virtualtourist.com/m/m/58bd4/