Eco Region Assessment 37. This ecoregion contains mostly arid landscapes as it lies largely in the rain shadow of the Cascade Mountains and includes most of the Northwest's lava fields. In the south, the plateaus grade into the basins and ranges of the Great Basin, which is typically drier and hotter. Precipitation falls uniformly throughout the year except for the summer months when little precipitation occurs.
Summers are hot and dry and winters are cold and dry.
Water from rainfall or snowmelt is slowly absorbed by the arid soils often resulting in significant runoff events. Most prevalent natural disturbance is scattered, low intensity ground fire usually set by summer thunderstorms. Water and wind erosion also are natural disturbance agents.