Challis National Forest, the more southerly of its two parts, lies primarily in Custer County, but also has major areas in Lemhi and Butte counties, as well as smaller areas in Clark and Blaine counties. It has a total area of 2,463,471 acres (3,849.17 sq mi, or 9,969.31 km2). There are local ranger district offices located in Challis, Clayton, and Mackay.
Salmon National Forest, which lies to the north, is primarily located in Lemhi County, with spillover into Valley and Idaho counties. It has a total area of 1,772,469 acres (2,769.48 sq mi, or 7,172.93 km2).[1] There are local ranger district offices located in Leadore, North Fork, and Salmon.
The combined forest headquarters are located in Salmon, Idaho.
Climate
There is a weather station at Middle Fork Lodge, which is on the western edge of Salmon–Challis National Forest.
Climate data for Middle Fork Lodge, Idaho 1991–2020 normals: 4480ft (1366m)
Sawtooth Wilderness (only about 5.5% of this wilderness lies with Salmon–Challis NF; most of it lies within Boise NF; part of it lies within Sawtooth NF; all of it is managed by Sawtooth National Forest)[4]