This Ecosection is the northern portion of the Southern Rocky Mountain Trench. This Ecodomain covers the southern interior plateau and is an extension of the dry climate regime that occupies the interior of northern Mexico and the northwestern United States. Its two most commonly recognized climates are arid desert and semiarid steppe. In British Columbia this Ecodomain is represented by only one Ecodivision. This Ecodivision occurs within the Dry Ecodomain in southern British Columbia and includes the leeward ranges of the Coast Mountains, the Thompson Plateau, the Clear Range, the Okanagan Range, and the western side of the Okanagan and Shuswap highlands.
Winters are cold and the summers are warm to hot.
Vegetation in the valleys and basins is typically steppe or bunchgrass prairie that may contain sagebrush or occasional ponderosa pine or Douglas-fir. At higher altitudes, subalpine coniferous forests can become established. In British Columbia this Ecodivision is represented by only one Ecoprovince. This Ecoprovince lies east of the crest of the Coast and Cascade ranges and west of the Columbia Mountains. It is the southernmost part of the Interior Plateau system.