Based on the Köppen climate classification, Bastion Peak is located in a subarctic climate with cold, snowy winters, and mild summers.[3] Temperatures can drop below -20 °C with wind chill factors below -30 °C. Precipitation runoff from Bastion Peak drains into tributaries of the Athabasca River on its east side, and tributaries of the Fraser River from the west side.
^Peel, M. C.; Finlayson, B. L. & McMahon, T. A. (2007). "Updated world map of the Köppen−Geiger climate classification". Hydrol. Earth Syst. Sci. 11: 1633–1644. ISSN1027-5606.