Shreveport's weather is hot and humid. Expect to wear cool clothes well into November and even December. While the fall weather does cool off a bit, it doesn't really get cold until January. Don't expect a white Christmas. Snow is so rare that people go outside to marvel at a light sleet. If it does snow, be prepared for all activity to stop. There are four noticeable seasons, but summer is the only one that lasts a significant amount of time. Spring is beautiful, with the campus grounds covered in flowers and the temperature perfect for lying out in the grass. If you stay on campus during the summer, though, don't go outside unless it's absolutely necessary. Every building is air-conditioned. Central air is your best friend in Louisiana. Not having it is unthinkable.
In terms of clothes, bring summer clothes for the fall semester and a light jacket. It usually doesn't get cold until the beginning of spring semester, but it's a good idea to have a small coat for slightly chilly days. One good thing about the warm weather is that sports can be played year-round. There are ultimate Frisbee games going on several nights a week. Unfortunately, the sporadic rain in Louisiana gets in the way. The campus has pretty good drainage, but there are some areas that turn into small lakes during a thunderstorm. Other than the heat and the random thunderstorms, there's no drastic weather in Shreveport. It can be fun to watch other people shoveling snow on TV while you sit around in shorts and a tank top, thinking about going outside to lounge in the sun.