Why is the weather wet?

Wet weather means high water content in the air, measured by humidity.

Simply put, humid weather is mainly caused by atmospheric circulation. The atmosphere flows regularly seasonally, forming a monsoon.

In China, there are Bay of Bengal and South China Sea in the southwest, arid inland in the northwest and East China Sea, Yellow Sea and Bohai Sea in the east.

So if the monsoon blows from the sea, it will bring a lot of water vapor, increase the water content of the air and make the weather humid.

On the contrary, if the wind blows from the inland and there is little water, the weather will be dry.

What it says above is the general climate. As for the microclimate caused by the topography and surrounding environment in some areas, it is another matter.

Small science, not rigorous, for your reference.