The weather in Durham is a lot of things, but "predictable" is not one of them. On the whole, it’s very pleasant, but temperatures and conditions can swing from the high end of the scale to the low end with little warning. Durham is kind of like Mother Nature’s little freak experiment, so you'll need your entire wardrobe. The beginning and end of terms are marked by some extremely hot and humid days, and no one enjoys the two or three long weeks of rain—a time when many students try to remember what it was like to walk home without being soaked to the shins. There are also a few cold weeks in the winter, and one or two snow "storms" (a few inches), which leave the entire area positively bewildered (but stunningly picturesque). So be sure to bring a good winter coat and a pair of rain or snow boots!
At Duke, you’re more likely to be concerned about heat stroke than frostbite, but be prepared for both (and every condition in between). Remember, though, that in between the extremes, Duke has many days that are breathtakingly beautiful, particularly in the fall. You won't want to miss those!