The rain shadow effect from the Cascade Range creates a wetter, greener environment in western Oregon and drier conditions in eastern Oregon.

The rain shadow effect from Oregon’s Cascade Range significantly influences the state’s climate, resulting in wetter conditions in the west and much drier conditions in the east. As moist air from the Pacific Ocean moves eastward, it rises and cools when it encounters the Cascade Mountains, causing substantial rainfall on the west side. Once this air crosses the peaks and descends on the eastern side, it has lost most of its moisture, leading to a dry, arid climate in eastern Oregon. This geographic feature shapes Oregon’s varied landscapes, making the western region lush and green while the east remains semi-arid.