The best time to visit Ha Giang is October and early November, when the buckwheat flowers bloom across the Dong Van plateau. The weather is cooler and generally clearer than in summer, the rice harvest in the lower valleys is underway, and the combination of the pink buckwheat blooms against the grey limestone makes for the most photogenic landscapes of the year. This is also the busiest time, so book guesthouses in advance for Dong Van and Meo Vac.
September is a good alternative: the buckwheat hasn't flowered yet but the terraced fields are lush green, the weather is drier than the July–August wet season, and there are noticeably fewer tourists. March to May is the spring option — flowers in the valley, milder temperatures — though the plateau can still be cold and overcast.
July and August are the wet season: roads can be dangerous, landslides are possible, and the views are often blocked by clouds. January and February are cold — temperatures on the high plateau drop below 5°C at night, and frost is possible — but the misty winter landscape and relative absence of tourists appeals to some visitors. The Chinese New Year period (Tet) sees some minority markets and festivals but also increased domestic tourism.