The best time to visit Tibet is from April to October, during which the weather is the best, neither too hot nor too cold. You can get a clear view of the most tourist attractions in Tibet. Besides, the oxygen content of the air is higher than at other times, which is helpful indeed in reducing the risk of getting altitude sickness. July, August and September are the peak tourist season, so the price is relatively higher. It’s advised to avoid the Chinese National Holiday (Oct 1st to 7th) when millions of Chinese people head to Tibet and you have to enjoy the scenic spots with a lot of people.