Spring: moms, dads, and prospective students. Fall: new kids and guides.
In the hotels and around town, we see families with college-age kids. In the spring and summer, we speculated that these were mom and dad taking the kids on college tours. Look around the campus, maybe interview with admissions or alumni. Certainly what I did at that age. In August or September, they are probably incoming freshmen in town early for orientation.
Toward the end of the week before Labor Day, there is a new phenom: small herds of a dozen-ish students being led around by an alpha. These are, I conclude, orientation walks: a knowledgeable student, probably a very experienced old hand (i.e., a sophomore), guiding walking tours for incoming freshpersons, pointing out important buildings, streets, transportation locations. The weather is still very warm and little sticky. All the kids are in loose shorts, all with backpacks, all with water bottles. And many with phones, bringing up the rear while texting something to someone. The alpha guide is smart enough to wear a hat. Or carry and umbrella, depending on the day.