According to the Köppen [climate classification] system, Mount Stepo is located in a subpolar oceanic climate zone with cold, snowy winters, and cool summers. Weather systems coming off the North Pacific are forced upwards by the mountains, causing heavy precipitation in the form of rainfall and snowfall. Winter temperatures can drop to 0 °F with wind chill factors below −10 °F. This climate supports a small unnamed glacier on the west slope of the peak.