The best time to visit is March to August. During this period, the weather is favorable and the wild flowers are in bloom here and there. September or October is also a favorable month. This is fall harvest time and the entire plateau becomes a golden world.

Tips
1. Because of the plateau climate, the weather of Shangri-La is always varied and unsettled. Even in August, you can find a snow flake dropping from the sky. So no matter when to go, you should be prepared with some warm clothes. And the ultraviolet radiation here is very strong so wear a sunhat and sunglasses. Ladies, especially, shouldn't forget to use sun block.
2. After arriving in Shangri-La, you may have altitude stress: shortness of breath, chest tightness and dreaminess. At this moment, you must not do strenuous exercise or drink alcohol but should have a good rest and keep warm.
3. Before you drink a toast proposed by Tibetans, you should moisten your index fingers with the liquor, flick this finger three times, and then say "Zha-xi-de-le". ("Zha-xi-de-le" means "as lucky as one's wishes" in Tibetan.) According to the Tibetan customs, you should sip three times and the host will refill your cup three times. After that, you ought to drink up. If you really can not stand much liquor, you can tell the host politely.
4. In a Tibetan family, there is an order to the drinking of butter tea. The elders, parents, guests and the persons they pay respect to will drink first; then, the host himself and lastly the younger people. The host will add the butter tea into your cup from time to time. So, if you have drunk enough, you should use your palm to cover the cup mouth and the host will understand. When you leave the family, you should leave a little buttered tea in your cup, which signals for your respect to the host.

Please click Proper Etiquette to know some taboos of Tibetans.