page_title: Great Sand Dunes National Park and Preserve
section_title: Climate
hierarchical_section_title: Great Sand Dunes National Park and Preserve / Climate
caption_attribution_description: NPS/Patrick Myers
context_page_description: Great Sand Dunes National Park and Preserve is an American national park that conserves an area of large sand dunes up to 750 feet tall on the eastern edge of the San Luis Valley, and an adjacent national preserve in the Sangre de Cristo Range, in south-central Colorado, United States. The park was originally designated Great Sand Dunes National Monument on March 17, 1932, by President Herbert Hoover. The original boundaries protected an area of 35,528 acres. A boundary change and redesignation as a national park and preserve was authorized on November 22, 2000, and then established by an act of Congress on September 24, 2004. The park encompasses 107,342 acres while the preserve protects an additional 41,686 acres for a total of 149,028 acres. The recreational visitor total was 527,546 in 2019.
  The park contains the tallest sand dunes in North America. The dunes cover an area of about 30 sq mi and are estimated to contain over 1.2 cubic miles of sand. Sediments from the surrounding mountains filled the valley over geologic time periods.
context_section_description: The Great Sand Dunes are located in the high elevation desert of the San Luis Valley at about 7,694 ft (2,345 m), just west of the Sangre de Cristo Range. The dunefield's Köppen climate classification type is cold semi-arid (BSk), while the mountainous preserve's climate type is warm-summer humid continental (Dfb), at an average elevation of 10,970 ft (3,344 m). Summer high temperatures are moderate with an average high temperature slightly above 80 °F (27 °C) in July, which is the warmest month. The park's large spread between high and low temperatures, about 25–30 °F (14–17 °C), is typical of a high desert climate. Low temperatures during winter nights can be extremely cold, with average low temperatures well below 32 °F (0 °C) and record low temperatures below 0 °F (−18 °C) from November through April. Precipitation is very low on the dunes, averaging just 11.13 inches (283 mm) of rainfall per year. A high evaporation rate on the dunes qualifies the area as a desert, even though precipitation exceeds 10 inches (250 mm).
  Spring conditions vary greatly, from mild and sunny to cold and snowy, with occasional high winds in the afternoon. March is the snowiest month, though some days are above 50 °F (10 °C). In late spring, when Medano Creek usually has its peak flow, snow and high winds are still possible. In summer, daytime high temperatures average 75–80 °F (24–27 °C); however, sand surface temperatures can soar to 150 °F (66 °C) on sunny afternoons. Summer nights are cool—the park is located 8,200 ft (2,500 m) above sea level—with nighttime temperatures often dropping below 50 °F (10 °C). Afternoon thundershowers are common in July and August with cool winds, heavy rain and lightning. Fall is generally mild, with Indian summer days when temperatures reach or exceed 60 °F (16 °C), but nighttime temperatures drop below freezing. Occasional fall storms bring icy rain or snow. Cold temperatures well below freezing are typical in winter, although the sunshine is generally abundant and the dry air doesn't feel as cold as more humid areas. The average winter high temperatures are just above freezing even in January, which is the coldest month.
caption: Snow-covered dunes and Mount Herard
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