Oregon: Geography and climate

While almost all Washington state vines are planted in the rain shadow and semi-desert east of the Cascade Mountains, most Oregon vines are directly exposed to the marine airflow of the Pacific ocean, giving milder winters but cooler and wetter summers than Washington. Oregon is notoriously wet, yet in most years the majority of the rain falls between October and April, not during the crucial part of the growing season. In a late-ripening year, however, rain during harvest can cause rot and dilution, while flocks of migrating birds can ravage a vineyard within hours.