It is located on the border between Linn and Jefferson counties, about 18 mi (29 km) northwest of Sisters, between the prominent volcanic horns of Three Fingered Jack to the north and Mount Washington to the south.

Several other smaller volcanoes, including cinder cones and tuyas, are found near the summit of the pass.

This expedition was led by Andrew Wiley, who reportedly climbed a tall tree on a mountain near Lost Prairie to help determine the route.

[2] Santiam Pass has a subarctic climate with cold, extremely snowy winters and mild to sometimes warm summers with occasional precipitation.

Santiam Pass's crest location allows for some of the highest snowfall totals in the US to fall onto it and for more summer rainfall than the surrounding lower elevated areas may see as well.