One biome that is found within the boundaries of Arches National Park is desert. Some geographers describe desert as places where evaporation exceeds precipitation. Precipitation in the hot desert averages 5 to 10 inches per year. Temperatures soar above 100 degrees Fahrenheit in the summer and drop below freezing in the winter. However, the hot weather affects animals who lived there. Some animals only come at night when its more cool and fresh for them. Utah's cold deserts generally range from 4,000 to 6,000 feet in elevation and can be characterized as broad valley and broke, rolling hills. Annual rainfall is usually less than 11 inches. Another biome that is found at Arches National Park is grassland. Grassland biomes are large, rolling terrains of grasses, flowers and herbs. The precipitation is so erratic that drought and fire prevent large forests from growing. Grasses can survive fires because they grow from the bottom instead of the top. Their stems can grow again after being burned off. The soil of most grasslands is also too thin and dry for trees to survive. This helps the unique plants in the Arches to survive. In the winter, grassland temperatures can be as low as -40° F, and in the summer it can be as high 70° F. There are two real seasons: a growing season and a dormant season. The growing season is when there is no frost and plants can grow (which lasts from 100 to 175 days). During the dormant (not growing) season nothing can grow because its too cold.