Lush western forest, NPS photo, B. GraffFog drifting over Continental Divide, NPS photo, D. RestivoLightning over St. Mary Lake, NPS photo

Climate is the pattern of variation in temperature, humidity, wind, precipitation, and other meteorological variables in a given region over long periods. In contrast, weather describes the present condition of these variables over short time periods.

Location plays a key role in how the climate affects the landscape in the Crown of the Continent Ecosystem. The Continental Divide splits the Crown and is the general boundary between the more dominant maritime air masses, which tend to bring moisture and moderate temperatures from the Pacific, and continental air masses, which tend to be colder and drier air from northern Canada. The Continental Divide forms a wall that forces maritime air masses to rise, causing cooling and the ensuing release of moisture. This helps to support the more lush forests on the western side of the Crown. 

Precipitation is highly variable with higher peaks receiving much more rain and snow. However, even at the same elevation and approximate latitude, location determines annual precipitation: Fernie, B.C., west of the Continental Divide, receives 47 inches of moisture annually, while Pincher Creek, about 40 miles east, receives just 18 inches of annual precipitation. 

Winds are a factor as well. Waterton is one of the warmest areas in Alberta thanks to winter Chinook winds that carry very dry, warm air. Temperatures in Waterton may be as much as 35-55 °F higher than the frozen prairies to the east.