Acker Peak is a 10,988-foot mountain in Yosemite National Park, California, ranking as the state's 665th-highest summit. It was named for park official William Bertrand Acker, and the U.S. Board on Geographic Names officially adopted the name in 1932. The first recorded ascent followed on July 27, 1945, when Arthur J. Reyman reached the summit. The peak lies in an alpine climate zone, where weather systems moving in from the Pacific are forced upward by the Sierra Nevada, bringing rain and snowfall to the range.