Polar Bear forgot to mention the wind which can be almost constant in Wyoming. I live in Colorado and regularly ride around Aspen, Vail and Steamboat as well as into Wyoming. Temperature variations can be dramatic. I have a BMW phase change jacket which is great for those temperature changes. I highly recommend them. Those of you from the East may also not realize that no matter how warm our days may be, it always cools off in the evening and you will want a jacket after the sun goes down. Even on days when the temperature reaches into the 90s you can expect it to cool off to the low 60s or even into the mid 50s. Moot