Climate
The Köppen classification depends on average monthly values of temperature and precipitation. The most commonly used form of the Köppen classification has five primary types labeled A through E. These primary types are A) tropical, B) dry, C) mild mid-latitude, D) cold mid-latitude, and E) polar. The five primary classifications can be further divided into secondary classifications such as rainforest, monsoon, tropical savanna, humid subtropical, humid continental, oceanic climate, Mediterranean climate, desert, steppe, subarctic climate, tundra, and polar ice cap.
Climate of Oregon
According to the Köppen climate classification, most of Western Oregon has a temperate oceanic climate (or Do type), which features cool summers, and wet winters with frequent overcast and cloudy skies. Eastern Oregon falls into the cool arid (or BSk type), which features drier weather.