Summer rain jacket recommendations
In my personal experience, anything you wear while riding that is even moderately water proof will trap heat and sweat and for me, I will end up just as wet if I had ridden with or without the jacket.

GoreTex and the like are just riding an edge of being helpful.  Short rides, cool temps, perfect.  Long rides, doesn't matter, you are going to get wet.  From the inside or the outside.  :)