The best time to visit Sanya is from November to April. During this time, Sanya has moderate temperatures, plenty of sunshine and little rain, making it perfect for outdoor activities and beach vacations.

The characteristics of different months are as follows:

Spring (March to May): the weather is warm for vacations, beach and island excursions.
Summer (June to August): peak tourist season with high temperatures for water activities, but sun protection and hydration are required.
Autumn (September to November): the weather is suitable for vacationing and enjoying the beach, and seafood and fruits are more plentiful.
Winter (December to February): cooler temperatures and cooler waters, not suitable for swimming, but you can experience the local culture and traditional festivals.
Suggestion:

If you want to avoid the peak of crowds, you can choose to visit during the off-season (e.g. summer), when there are fewer tourists and prices are relatively cheap.
If you like water activities, summer is the best choice, but you need to pay attention to sun protection and hydration.
If you want to experience the local culture, winter is also a good choice.