The date is September 8, 1900, the night before a massive hurricane strikes the coast of Galveston, Texas, killing between 6,000-10,000 people. Thirty-eight-year-old Isaac Monroe Cline is a meteorologist who heads the US Weather Bureau office in Galveston. He lives in a house on stilts with his wife Cora and their three daughters: 12-year-old Allie May, 11-year-old Rosemary, and 6-year-old Esther Bellew. Also living in the house is Joseph, Isaac's younger brother who works under him at the Weather Bureau.

Although US Weather Bureau agents in Cuba are unperturbed by a storm that passed over the island a few days earlier, Isaac can't sleep. Despite the Bureau's belief that the storm will lose its strength before making landfall in Louisiana or Texas, Isaac is troubled by the sound of deep-ocean swells falling on the beach three blocks from his house. Moreover, Cuba's own meteorologists disagree with their American counterparts about the size and character of the storm.

At dawn, Isaac rides his horse-and-cart through the glittering streets of Galveston: “It was a gorgeous morning" (10). The biggest cotton port in the country, Galveston is in competition with Houston to be the preeminent city in Southeast Texas. Referred to by the New York Herald as "the New York of the gulf" (12), Galveston is said to have "more millionaires per square mile than Newport, Rhode Island" (13).