What is an autumn rain and a cold poem?

An autumn rain and a cold, fallen leaves are full of frost. The night will be over, I lie in bed listening to the sound of wind and rain, in a daze in my dream, riding an armored horse across the frozen river to the northern battlefield. According to the relevant information, this is a sentence in the poem "Two Feelings at the Hedge Gate in Autumn Night, Part I" by the Tang Dynasty poet Wang Jia. The theme of this poem is to describe the coldness of autumn rain, which shows the poet's profound understanding of autumn scenery.