The story begins in Dakota Territory on a hot August day in 1880 as Laura and her father ("Pa") are haying. Pa tells Laura that he knows the winter is going to be hard because muskrats always build a house with thick walls before a hard winter, and this year, they have built the thickest walls he has ever seen. In mid-October, the Ingallses wake with an unusually early blizzard howling around their poorly insulated claim shanty. Soon afterward, Pa receives another warning from an unexpected source: a dignified old Native American man comes to the general store in town to warn the white settlers that there will be seven months of blizzards. Impressed, Pa decides to move the family into town for the winter.
Laura attends school with her younger sister, Carrie until the weather becomes too severe to permit them to walk to and from the school building. Blizzard after blizzard sweeps through the town over the next few months. Provisions begin to run low, as the townspeople had been depending on the trains to bring them supplies, but the frequent blizzards prevent the trains from getting through. Eventually, the railroad company suspends all efforts to dig out the train, stranding the town. For weeks, the Ingalls subsist on potatoes and coarse brown bread, using twisted hay for fuel. As even this meager food runs out, Laura's future husband Almanzo Wilder and his friend Cap Garland risk their lives to bring wheat to the starving townspeople– enough to last the rest of the winter.
As predicted, the blizzards continue for seven months. Finally, the trains begin running again, bringing the Ingalls a Christmas barrel full of good things– including a turkey, still frozen. In the last chapter, they sit down to enjoy their Christmas dinner in May.