Planning for the weather is a good way to make your trip to Sanya Downtown relaxing and enjoyable, especially when you’re splurging. The hottest months are usually June and May with an average temp of 82°F, while the coldest months are January and December with an average of 71°F. The rainiest months in Sanya Downtown are July, October, August, and September, with each month seeing an average of 10 inches of rainfall.