The dry season — November to April — is the most comfortable time to visit Cu Chi. Temperatures stay in the low to mid thirties but the humidity is lower and rain is rare. The tunnels themselves are underground and maintain a relatively constant temperature of 25–30°C year-round, so the season affects the above-ground portions of the visit more than the underground tour.
In the rainy season (May to October), the jungle above the tunnels becomes muddy and the paths between exhibits can be slippery. The site remains open but is less pleasant. The heavy rains come in afternoon downpours rather than all-day drizzle, so morning visits are generally drier.
Weekdays are significantly quieter than weekends. Vietnamese school groups and family visits are concentrated on Saturdays and Sundays, and the Ben Dinh site in particular can feel crowded on a weekend morning. Coming on a weekday, especially in the morning before tour buses from HCMC arrive, gives a noticeably different experience.