Alta Mountain is a 6,275-foot peak in Washington’s Cascade Range within the Alpine Lakes Wilderness and Wenatchee National Forest, with runoff feeding tributaries of the Yakima River. It rises in one of the range’s most rugged landscapes, marked by craggy ridges, granite walls, deep glacial valleys, and hundreds of mountain lakes. That terrain formed over millions of years through volcanic activity, accreted terranes, and repeated Pleistocene glaciation, with the last major retreat beginning about 14,000 years ago and helping carve the region’s U-shaped valleys. In the marine west coast climate zone, Pacific storms bring heavy rain and dense snow, while July through September usually provide the clearest conditions.