Choosing between may and might is one of the most difficult decisions you will ever make.
Okay, maybe not, but it's still hard. Why?
These days, the two are basically interchangeable. We're going to tell you the rule for when to use each one, but you'll never really be wrong in choosing one over the other. In most situations, it's a win-win. We say "most" because your English teachers might not be so flexible.
You want to use may if something is likely to happen. If you move to New York City, you may become a Yankees fan. Your Red Sox cronies may not be too pleased with you, though.
When something is more of a stretch, go ahead and use might. You think baseball is the most boring sport ever invented. One day you might enjoy watching, but you're not promising anything to your new girlfriend, the Giants' #1 Fan.
"Considering that I was awake until midnight writing a paper, I may sleep in tomorrow. Don't even think about waking me up, Mom, because I might just punch you in the face."
In the sentence above, you're tired (and rightly so). You'll probably sleep in, so the verb may works best there. Would you actually sock your mom in the face? We don't know for sure, but we're guessing you wouldn't. So you'd plug in might there since the action probably won't happen. If you do end up decking your sweet, sweet mother, we're calling the cops—and your grammar is wrong.