The second Saturday in August is reserved for the Blues n' Brews festival in Rock Springs each year. Its a festival that I've wanted to check out since I moved here, but never had until this year! And I think I'll go back.
Blues n' brews is held in Bunning Park which is surrounded by trees so its nice and shady, which equals not hot. They bring in bands all day till about 10 pm and have food and brews from several different breweries from around the area. A lawn chair and some friends are pretty much required.
I don't own a single blues cd, but I just like live music and so it doesn't even matter if I don't know a single word or song for that matter. So reserve the second Saturday next August and come visit me!