The most populous county in Oregon is Multnomah County, where Portland, the Pacific Northwest's port city, is located. With a population of 652,503 as of 2020, Portland is the largest city in Oregon, the 26th largest in the United States, the sixth largest on the West Coast, and the second largest in the Pacific Northwest, after Seattle. The Portland metropolitan statistical area is home to around 2.5 million people, making it the 25th most populated in the US. Approximately half of Oregon's population resides in the Portland metro area.
Portland's climate is a warm-summer Mediterranean climate that is slightly below a hot-summer Mediterranean climate. The city experiences mild and rainy winters and warm and dry summers. Due to its location in the direct path of the stormy westerly flow, Portland experiences fluctuating, wet, and overcast weather conditions during fall, winter, and spring. When the North Pacific High is at its northernmost point in the middle of summer, the city experiences warm and dry summers.