What's the best month for a junior-year college tour?

Short answer: Spring of junior year (March–April) is the single best window: students are on campus, classes are in session, and the visit doesn't eat application-season time. Avoid August (many campuses empty out) and final-exam weeks in early May.

March and April beat October and November for one reason: the campus is mid-semester and full of students you can actually ask questions of.

Summer visits work for itinerary flexibility but most dorms are empty and tours run on skeleton staff — fine for a first look, not for a final decision.