According to the Mohave Indians, "Crazy Weather" lasts four days—four days of the damndest, hottest weather ever, anywhere. And in the summer of 1905, the Mohave Valley of the Colorado River is hit with one of the worst spells. For South Boy, a 14-year-old ranch kid caught between a childhood he is leaving behind and an adulthood he is not yet ready for, it brings a crisis as intense as the summer heat.
In trouble with the law and his parents and afraid of being sent away from his Indian friends to missionary boarding school, South Boy runs away. With his Mohave pal, Havek, and his prize possession, a nickel-plated revolver, he heads upriver towards a rumored war with the Piutes. Together they hope to satisfy their hunger for life and adventure. But according to their hawk dreams, as interpreted by a Mohave dream-teller, they may become real heroes of the battle.
Dodging the law (in the person of Joe, a half-breed reservation policeman), they run, fish, fight, learn about girls, sex and love, try to save the life of a great old Mohave warrior, and suffer the disillusionment of seeing a hero dethroned.
The war turns out to be one lunatic Piute on a murderous rampage. For South Boy, tracking down and mortally wounding the Piute becomes an ugly, unsatisfying business. War isn't what it's cracked up to be. Worse, Havek is witched, out of his head and possibly dying.
In coping with this new crisis and saving Havek's life, South Boy discovers self-reliance. He also learns a valuable lesson from Joe, whose competence and brains win South Boy's respect, and whose understanding and sympathy for South Boy restores the boy's self-respect.
This new sense of responsibility brings a final crisis to South Boy. He decides that he and Havek must go back and save the wounded Piute left to die. But Havek, intent on his future as a hero of his people, feels no obligation and wants only to go home. They part, still friends, but not quite in the same way. South Boy, alone and unhappy, tracks down the Piute only to face death from the dying Indian's knife. His rescue by his watchful protector, Joe, coincides with the thunderclap that brings a deluge of rain. The crazy weather is broken.
Like the fresh grass that will be springing up in the desert after the rain, South Boy sees new hope for his family's ranch and for himself. He is already thinking of his future. He will go home, perhaps to school, but on his own terms. His childhood is over, only to fade into a dream.