It is important to avoid washing fresh blueberries before you store them, as some of the residual moisture can lead to mold growing on them. You will be able to store blueberries at room temperature, but only for about one to two days.
When you refrigerate your blueberries, they should be kept at a steady 40 degrees or so to avoid any mold forming or going bad. Make sure that if you do refrigerate your blueberries that you store them in a container which is tightly covered so you can avoid any air from getting in or out.
It is important to do this so you keep them from getting moldy over time.