Portland (OR) Climate by Month
Portland has a Mediterranean climate, which means a pleasantly warm summer and mild winters. Sometimes temperatures during winter will drop below zero, but this will only be at night.
It can rain quite a bit, especially during winters. The best time to visit Portland in the state of Oregon is from May to September. During this period you have a warm temperature and almost no precipitation.
Average day and night temperature
The climate in Portland is known for significant temperature differences throughout the year, making the weather dynamic. Average daytime temperatures range from a comfortable 28°C in August, the warmest time of the year, to a chilly 7°C during cooler months like December. At night, temperatures typically average around 2°C during these months.
The mean minimum and maximum temperatures throughout the year
Precipitation and rainy days
Portland has a notably wet climate with abundant precipitation, recording 1050 mm of rain/snowfall per year. Significant seasonal changes in precipitation occur throughout the year. During the wetter season, December receives heavy rainfall, averaging 179 mm of precipitation, recorded across 20 rainy days. In contrast, the drier season, August brings less rainfall, with 11 mm over 3 rainy days.The mean monthly precipitation over the year, including rain, hail and snow
The average number of days each month with precipitation
Sunshine over the year
Seasonal changes in sunshine hours are quite dramatic in Portland. While July receives considerable daily sunshine with up to 11.1 hours, December marks the darkest time of the year, where sunshine is scarce with only 2.1 hours of sunlight per day.Monthly hours of sunshine
Daily hours of sunshine
Average humidity
The relative humidity is moderate throughout the year in Portland.
Relative humidity over the year
Average wind speed
The mean wind speed over the year in Portland ranges from 2°C in September to 4°C in January.
The mean monthly wind speed over the year (meters per second)
The best time of year to visit Portland in the United States of America
During the months of May, June and September you are most likely to experience good weather with pleasant average temperatures that fall between 20°C and 26°C.Other facts from our historical weather data:
Most rainfall (rainy season) is seen in November and December.
Yes, the months of July and August are very dry.
August has an average maximum temperature of 28°C and is the warmest month of the year.
The coldest month is December with an average maximum temperature of 7°C.
December tops the wettest month list with 179 mm of rainfall.
August is the driest month with 11 mm of precipitation.
July is the sunniest month with an average of 332 hours of sunshine.
No idea where to travel to this year? We have a tool that recommends destinations based on your ideal conditions. Find out where to go with our weather planner.
