Considerably east of and isolated from the main crest of the Northern Rockies, they are one of the few points of significant elevation in the immediate area and are considered one of Montana's island ranges.

[5] The Big Snowies feature a long, relatively level east-west summit ridge, rising above timberline, that culminates in Greathouse Peak, the highest point in the range.

[5] Wildlife includes rattlesnakes and pronghorn on the grass-covered lower elevations and deer and black bear higher up.

Lewistown 11 SSE is a weather station on the northern slopes of the Big Snowy Mountains, situated at an elevation of 4965 ft (1513 m).

[10] Lewistown 11 SSE has a humid continental climate (Köppen Dfb), with long, snowy winters and short, warm summers.