In the winter, it gets down into the 20's and 30's (-10 to 0s deg C), while in the summer, it does reach the 90's (high 30s deg C) and low 100s 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. 

Best months for weather: 15 April to 31 May, and then 1 Sept to 15 Oct.  Leaves turn middle of October.  Best time for events and festivals? July, August, September. 

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.  Daily temp variance is about 15 to 20 deg F. any time of the year.