Those who are going to be attending the Bro Exchange in Boulder next week should be aware that this time of year daily afternoon thunderstorms may be expected. Also, the temperatures at night are starting to fall, and temps in the fifties will be expected. If you plan to go up into the mountains it may even get into the thirties at night, depending on how high you go up. At 10,000' you should expect overnight lows in the low forties to high thirties, with always a possibility of frost at that altitude.
Boulder will not be so extreme but it's possible for it to get quite chilly at night. So be warned!