What does it mean to predict rain by fortune telling?

Journey to the West Divination Counting Rain Sets

Episode 15

The raindrop of the Dragon King's fortune telling in Journey to the West is the fifteenth episode of the sequel to Journey to the West, because anyone who first read the sequel to Journey to the West knows that the raindrop of the Dragon King's fortune telling is in the episode of Heishui River.

The Journey to the West is the first romantic novel with chapters and sections in ancient China. There are hundreds of books in The Journey to the West published in Ming Dynasty, and there is no author's signature. Wu Yuzhuan, a scholar in Qing Dynasty, and others first suggested that The Journey to the West was written by Wu Cheng'en in Ming Dynasty.