Huanglong is open year-round, but the experience varies considerably by season.
April to November is the standard visiting season, with a ¥200 entrance fee. The pools are at their most colourful between August and November, when autumn light strikes the calcium deposits at better angles and the surrounding trees add seasonal colour. Summer (June–August) is the peak tourist period with the most crowded conditions; the pools are full but the queues at the cable car and the top viewing platforms can be long.
December to March sees entrance fees drop to ¥60 — a significant reduction. Winter visiting has real rewards: far fewer crowds, and the pools take on a frost-edged quality where ice forms at the margins of the formations while the mineral water continues to flow through the centre. Snow on the surrounding peaks and the boardwalk railings adds to the atmosphere. The cold is genuine, however, and the altitude makes it feel more extreme than a ground-level temperature would suggest. Dress in layers regardless of the season.
Altitude sickness is a significant consideration. The park entrance is at 3,000 metres and the Five Colored Pool is at 3,700 metres. Visitors arriving directly from low-altitude cities without acclimatisation should expect headaches and shortness of breath. One night at altitude before visiting — in Songpan (2,850m) or even Jiuzhaigou (2,000m at the base) — reduces the impact.