Awful dandruff in the summer?

Every summer, my scalp itches like crazy and I have extremely bad dandruff. Like, I also have it, but as soon as summer starts, it gets uncontrollable. It's so itchy that I usually end up scratching til my head bleeds, which I know is bad, but it itches so much! It's usually in the same spot every year, too. I moisturize it and wash it and stuff, but at this point, I really don't know what to do. Suggestions?