I talk a lot in my job (lawyer) and in two of my primary hobbies (acting, umpiring). There are two common reasons for getting hoarse from too much talking:
1) Dehydration. Even if it's not super hot, keep drinking. I'm assuming you know all about that.
2) Using your throat to create volume. It's a natural thing to do, to tense up your throat when you yell, but it tears up your throat. So don't yell. Keep your throat relaxed and add more air; deepen your breaths, breathe from the diaphragm, and drop your pitch (which relaxes the vocal cords). If I could hear you, I could tell within seconds if you have this problem.
If neither of those help, time to see the doctor; a normal throat shouldn't get hoarse just from being used a lot (or I would have lost my voice twenty years ago
)