Spring
It is mostly rainy, misty and cloudy. Prepare shirts, sweaters and overcoats because temperatures are lower as you climb up higher altitudes. Wearing layers that could easily be taken on and off are convenient when you climb or hike on the mountain.
Summer
Summer time is the tourist high season. Summer on the mountain is cool, but you may still get burnt when the clouds clear. The rainfall is plentiful. This makes summer the best time to enjoy the Sea of Clouds, one of the famous four features of the mountain (the other three are the oddly-shaped pines, grotesque rocks and hot springs). Prepare summer clothes, sun protection. The temperature during night is low, so you also need to bring a jacket.
Autumn
The climate is most comfortable and the scenery is stunningly beautiful in autumn. Yellow Mountain is one of the best places to enjoy autumn foliage in China, looking down on the deciduous trees of the ravines and valleys. The national holiday another high season, so Mount Huangshan is crowded and it costs more to travel and stay at hotels.
Winter
Winter is freezing up on the mountain and spectacular snowscapes are seen every year. It's the low season, so the mountainside is much less crowded and it is much cheaper to travel. Prepare warm winter clothes, including fleece or down.