| Mystery Mountain | |
| Elevation Ft: | 9830. |
| Elevation Ref: | [1] |
| Prominence Ft: | 626 |
| Isolation Mi: | 0.80 |
| Parent Peak: | McGowan Peak (9,878 ft) |
| Map: | Idaho#USA |
| Label Position: | bottom |
| Map Size: | 240 |
| Part Type: | Protected area |
| Part: | Sawtooth Wilderness |
| Country: | United States |
| State: | Idaho |
| Region: | Custer |
| Region Type: | County |
| Coordinates: | 44.206°N -115.068°W |
| Coordinates Ref: | [2] |
| Range: | Sawtooth Range Rocky Mountains |
| Rock: | Granodiorite, Granite[3] |
| Age: | Eocene |
| Topo: | USGS Stanley Lake |
| Type: | Fault block |
Mystery Mountain is a 9830adj=midNaNadj=mid summit in Custer County, Idaho, United States.
Mystery Mountain is part of the Sawtooth Range which is a subrange of the Rocky Mountains.[4] It is situated 7miles west of Stanley, Idaho, in the Sawtooth Wilderness on land managed by Sawtooth National Forest.[2] The mountain can be seen from Highway 21 and from Stanley Lake. Precipitation runoff from the mountain drains to the Salmon River via Crooked Creek and Valley Creek. Topographic relief is significant as the summit rises over 3000abbr=offNaNabbr=off above Crooked Creek in 1miles. This mountain's toponym has not been officially adopted by the United States Board on Geographic Names.
Based on the Köppen climate classification, Mystery Mountain is located in an alpine subarctic climate zone with long, cold, snowy winters, and cool to warm summers.[5] Winter temperatures can drop below 0 °F with wind chill factors below −10 °F. Climbers can expect afternoon rain and lightning from summer thunderstorms.