Mount Nimbus is a 12,721-foot-elevation (3,877-meter) mountain summit in Grand County, Colorado, United States.The west side of the peak is in the Never Summer Wilderness, on land managed by Arapaho National Forest.Precipitation runoff from the mountain's lower northwest slope drains into headwaters of the South Fork Michigan River and all other slopes drain into tributaries of the Colorado River except a portion which is diverted by the Grand Ditch.The mountain's toponym was applied in 1914 by James Grafton Rogers,[6] and was officially adopted in 1932 by the United States Board on Geographic Names.[9] Due to its altitude, it receives precipitation all year, as snow in winter, and as thunderstorms in summer, with a dry period in late spring.