The mountain is situated west of the head of Finlay Reach of Williston Lake, and a remote 67 km (42 mi) south of Fort Ware in the Cassiar Land District.

[3] It rises 1,250 m (4,100 ft) above the south shore of Pelly Lake.

Precipitation runoff from the mountain drains into Pelly Creek, a tributary of the Ingenika River.

[2] Based on the Köppen climate classification, Pelly Peak is located in a subarctic climate zone with cold, snowy winters, and mild summers.

[4] Temperatures can drop below −20 °C with wind chill factors below −30 °C.