Originally Posted by supcom
I should think that, up until you get to the Rockies, you can survive a cold snap by either:
1. Putting all your clothes on, including rain gear (vapor barrier) and crawling into your sleeping bag.
2. Getting a motel room for the night.
Chances are once you get past the Appalachians, you'll be looking for cool breezes more than warm bags.
When you get to Pueblo, you certainly could get whatever you need to get through the mountains. Afterward, you can mail home whatever you don't need.
To give you some idea of the temperature differences, in June and July, the average high and low in Dodge City, KS is 90F and 60F, respectively. For Pueblo, it's about the same. For Breckenridge, CO, it's 70F and 39F, respectively (135 miles away). For Steamboat, it's 76 F and 45. You'll probably find similar temps all the way to Missoula.
One thing to remember is that from Pueblo to Breckenridge, you have to cross South Park. South Park is a hole compared to the mountains around it, and the temperature can fall even further. About the only other place you'll need a warm bag is when you get to Astoria. That's one cold place!