An updated version for the newly released 1991-2020 PRISM climate normals. Keeping as a unique file here from the previous version based on 1981-2010 normals, due to the changes in climate types across the state that have occurred.
Data sources: Köppen types calculated from data from PRISM Climate Group, Oregon State University, http://prism.oregonstate.edu; Outline map from US Census Bureau

-3°C isotherm used to distinguish temperate (C) and continental (D) climates. When a -0°C isotherm is used, much of the Csb climate areas found east of the Cascades becomes a Dsb, as these climates have a minimum monthly mean temperature between 0 and -3°C.
Own work
Adam Peterson