Natchez is in the Deep South and has the summers to prove it: June through August is hot, humid, and enervating. Spring (March–May) and fall (October–November) are the most comfortable and also coincide with the twice-yearly Natchez Pilgrimage, when private homes open for tours. Book accommodation well ahead if visiting during Pilgrimage weeks.
Winter is mild by most standards — temperatures in the 50s Fahrenheit — and the mansions are quieter and cheaper to tour. Christmas in Natchez includes several special events and the houses are decorated, making it one of the more pleasant off-season times to visit.