Why does the weather in Sanya have the title of four seasons like spring?

Sanya is located at the southernmost tip of Hainan Island, with north latitude1809' 34 ",east longitude1837' 27" and east longitude10856' 30 "-10940". Sanya has a unique climate, located at low latitudes, which is greatly influenced by the marine climate and belongs to the tropical marine monsoon climate. The annual average temperature is 25.4℃, the highest temperature is July, and the average temperature is 28℃; The annual sunshine time is 2563 hours; The average annual rainfall is1279mm. The four seasons here are like summer, so it can be said that there is no frost and snow in three winters, and bloom is always there in four seasons, which is known as "Hawaii of the East".