Portland sits at the confluence of the Willamette and Columbia rivers in northwestern Oregon, in a valley between the Coast Range and the Cascades at approximately 45.52°N, 122.68°W. It has a warm-summer Mediterranean climate (Köppen Csb) — with dry, mild summers and cool, exceptionally wet, grey winters.

Summer, from June to September, is warm, dry and sunny, with July and August the warmest — average highs around 26–27°C — with very low humidity and cool nights. Rain is scarce for months, and prolonged heatwaves have become a growing danger, as when a record 46.7°C was reached in the Pacific Northwest heat dome of June 2021.

Winter, from November to March, is cool, damp and famously grey, with December and January the coolest — average highs around 8°C and lows near 2°C. Rain falls on most days, usually as persistent drizzle rather than downpours, and snow is infrequent; the season is defined by unbroken low cloud rather than cold.

Portland receives around 950–1,000 mm of rain a year, overwhelmingly between November and April; the striking statistic is not the total but the frequency — rain falls on around 155 days a year, mostly as light drizzle, while July and August are nearly rainless. Live rainfall, humidity, and pressure readings for the city are shown in the panels above.

Portland's reputation for rain is about persistence, not volume: it receives less annual rainfall than New York or Atlanta, but spread across far more days as unbroken grey drizzle from November to April, before giving way to a brilliantly dry, sunny summer that is among the pleasantest anywhere.

To follow any single measurement in Portland more closely, use our live instruments: the online barometer for atmospheric pressure, the thermometer for temperature, the hygrometer for humidity, the anemometer for wind speed, the wind vane for wind direction, and the rain gauge for rainfall.