What season is written in the first two sentences of the poem?

The stream of the river has been flowing for less than a day, and white stones are exposed on the riverbed. The weather is getting colder and the red leaves on the branches are becoming scarce.

There is no rain on the winding mountain road, the smoke is misty in the dense pine trees, and the water vapor is heavy, as if to flow, and then the clothes of passers-by.

It's about the scenery in late autumn. Red leaves generally refer to maple leaves, which turn red in autumn. As the poem says, the sparse red leaves mean that the maple leaves are all withered, so it is late autumn.

As I said in the first sentence, Jingxi is a small stream. The white stone in Jingxi indicates that the water level of the stream is low. Generally, the water level will drop in late autumn!