In the winter, it gets down into the 20's and 30's while in the summer, it can reach the 90's with high humidity. Late spring is probably the best time to come here, or in early fall. Try to find a time when there are special events going on.
For the four seasons: Summer - pack shorts and T-shirts, a bathing suit and sun glasses. It's gonna be hot! Fall and Spring - these two are hard to guess: it snows in November some years and in others there is 80 degree heat, and the same goes for April. The best thing to do is to check the weather report for that week. Winter - pack warm, and bring lots of jackets.