Judging from the three-circle circulation map, Fangchenggang is about 30 north latitude. Why are there so many rainy days?

The three-circle circulation diagram is an ideal atmospheric circulation diagram. In fact, there are many factors that affect the atmospheric circulation, among which the thermal difference between land and sea will cause great changes in the related circulation. The climate of Fangchenggang is not only influenced by latitude position, but also by land and sea position, so there are many rainy days in the formation and influence of monsoon climate.