The Klamath Mountains are a mountain range in northwest California and southwest Oregon, the highest peaks being Mount Eddy (2744m / 9002') in Trinity County, California, and Mount Ashland (2296m / 7533') in Jackson County, Oregon. They have a varied geology, with substantial areas of serpentine and marble, and a climate characterised by cold winters with very heavy snowfall, and warm summers with limited rainfall. As a consequence of the geology, they have a unique flora, known as the Klamath-Siskiyou forests, which includes several endemic or near-endemic trees, such as Port Orford-cypress (Chamaecyparis lawsoniana), Foxtail pine (Pinus balfouriana spp, balfourinana), Brewer spruce (Picea breweriana) and Kalmiopsis (Kalmiopsis leachiana), forming one of the largest collections of different conifers in the world. The northernmost range of the Klamath Mountains are known as the Siskiyou Mountains.

Mountain ranges of California | Mountain ranges of Oregon | Geologic provinces of California

Klamath Mountains