The John Muir Wilderness encompasses approximately 584,000 acres in the Sierra and Inyo National Forests. It extends along the crest of the Sierra Nevada from Mammoth Lakes southeasterly for 30 miles, and then forks around the boundary of Kings Canyon National Park to Crown Valley and Mt. Whitney.
Elevations range from 4,000 feet to 14,496 feet at Mt. Whitney with many peaks above 12,000 feet. Deep canyons as well as beautiful meadows among the many lakes and streams characterize the Wilderness. The South and Middle Forks of the San Joaquin River, the North Fork of the Kings River and many creeks, which drain into the Owens Valley, originate in the John Muir Wilderness.
Stands of Jeffery and lodgepole pine, incense cedar, and red and white fir can be found on the lower western slopes of the Sierra Nevada. Higher up are lodgepole, whitebark, and western pine, red fir and mountain hemlock. The highest elevations are barren granite. Summer temperatures range from 25 to 85 degrees and there is usually a frost-free period from mid-July through August. In summer, afternoon and evening thunderstorms are common.