Planning for the weather is a good way to make your trip to Yushan relaxing and enjoyable, especially when you’re splurging. The hottest months are usually August and July with an average temp of 80°F, while the coldest months are January and December with an average of 48°F. The rainiest months in Yushan are June, May, July, and March, with each month seeing an average of 10 inches of rainfall.