Early June is a nice time to visit the mountains. Temps at Crested Butte should be in the mid-50's to 60's for highs and down to upper-20's at night. Peak wildflower bloom is in late June through early July (the wildflower festival starts July 5). Lots of stuff to see and do. Depending on the snow pack you might be able to go on a jeep tour but many of the mountain passes with still have snow.