 As a result, the air has lost much of its moisture and becomes hot and dry when it reaches the areas east of the coastal mountain ranges.These arid conditions are, in some instances, exacerbated in regions of extremely low altitude (some near or below sea level) by higher air pressure, resulting in drier conditions and adiabatic heating effects, some of these pocket deserts exist in valleys well north of the Canada–US border in interior British Columbia.What precipitation does fall generally does not last long, lost primarily to evaporation, as well as rapid runoff and efficient water uptake and storage by native vegetation.