Powderhorn, ColoradoPowderhorn is an unincorporated community and a U.S. Post Office in Gunnison County, Colorado, United States. The Powderhorn Post Office has the ZIP Code 81243.HistoryA post office called Powderhorn was established in 1880. Some say the community was named from a nearby landform in the shape of a powderhorn, while others believe an old powderhorn found near the town site caused the name to be selected.ClimateClimate type is dominated by the winter season, a long, bitterly cold period with short, clear days, relatively little precipitation mostly in the form of snow, and low humidity. The Köppen Climate Classification sub-type for this climate is "Dfc".