The Coast Range is not very high by comparison with the Cascade Mountains, but they have the important climatic effect of reducing the precipitation which falls in the Willamette Valley to about 40 inches from the 70 inches that typically falls on the Oregon Coast. The range extends virtually from the Columbia River south to Coos County. The mountains near the coast farther south are often mistakenly called the Coast Range, but are actually part of the Siskiyou Mountain Range.
