Spring (March–May) is the most comfortable time to visit. Temperatures range from the mid-teens to mid-twenties Celsius, the azaleas and magnolias are in bloom, and Mardi Gras falls in February or early March — the Spanish Town parade is one of the city's most distinctive events. The weather is warm but not brutal.
Autumn (September–November) is the other good window, particularly if you want to experience LSU football culture. Night games at Tiger Stadium are a defining Baton Rouge experience, but the city fills up completely on game weekends and hotel prices spike sharply.
Summer (June–August) is hot and humid, with temperatures regularly above 35°C and high humidity making it genuinely uncomfortable. Hurricane season runs June through November; August and September are the peak risk months. Most indoor attractions are heavily air-conditioned, which helps, but outdoor sightseeing is draining.
Winter (December–February) is mild — temperatures rarely drop below 5°C — but the city is at its quietest. The exception is Mardi Gras season, which builds from mid-January and peaks in February or early March depending on the year.