Cao Bang is divided into two distinct seasons: rainy season which lasts from April to September and dry season is from October to March. If you intend to travel to Ban Gioc waterfall, should go around August to September, this waterfall will be very breathtakingly beautiful. If you like to go to Cao Bang to see flowers, you can go to the end of the year around November, this is the Trichet flowers season (equivalent to Trichet flowers in Ha Giang)