Portland Weather Averages
Portland enjoys mild temperatures most days of the year. But the city's summer and winter weather contrast sharply in the amount of rain and sunshine.
This page gives detailed information on the annual temperature, precipitation, sun, humidity, wind and storm averages for Portland. The numbers here are historical averages based on climate data gathered near the Portland International Airport, located a few miles from downtown Portland.
|63 °F||annual average high||17 °C|
|46 °F||annual average low||8 °C|
Portland's coldest days of the year usually occur from mid December to early January when the daily maximum temperature averages 45 degrees Fahrenheit (7 degrees Celsius) and the minimum averages 36 °F (2 °C).
The year's hottest days are normally at the end of July and early August. The average temperature peaks then with daily highs of 83 °F (28 °C) and nighttime lows of 58 °F (14 °C).
|127 days||70 °F max. or more (21 °C)|
|116 days||40 °F min. or less (4 °C)|
Portland averages 16 days a year when the thermometer reaches into the 90s °F (over 32 °C). The temperature can climb above 100 °F (38 °C), but that's a rare event which happens on an average of just one day a year.
The thermometer dips to 32 °F (0 °C) or below on 29 nights a year. Portland doesn't usually ever get as cold as 10 °F (-12 °C). Typically on 2 days annually the temperature remains below freezing for the entire day.
|43.7 in||total precipitation||1111 mm|
|163 days||of rain or snowfall|
December is usually the wettest month of the year in Portland, while summer months are the driest.
|3.4 in||total snowfall||8.6 cm|
|3 days||with new snow|
December and January are the months when Portland is most likely to get snow.
|68 days||clear skies|
The sun's rays reach the ground in Portland during 48 percent of daylight hours on average year round, for a total of 2143 hours annually. Typically on 68 days a year the sky is mainly clear, with at most 30 percent cloud cover.
Sunlight in Portland averages 12 hours and 13 minutes a day. The shortest days of the year in mid December have 8 hours and 42 minutes of daylight. The year's longest days in mid June last 15:41 from sunrise to sunset.
|73 %||average humidity|
The annual average for relative humidity in Portland ranges throughout the day from 85 percent at 4:00 am to 59 percent at 4:00 pm.
|Local Time||1 am||4 am||7 am||10 am||1 pm||4 pm||7 pm||10 pm|
|7.9 mph||wind speed average||12.7 kph|
January is usually the windiest month for Portland, while the wind is generally calmest during early autumn.
|5 days||precipitation of 1 inch (25 mm) or more|
|1 day||snowfall of 1 inch (2.5 cm) or more|
|7 days||with thunderstorms a year|
About once a decade, Portland gets a major snowstorm that leaves 5 to 10 inches (13 to 25 cm) of snow.
Thunderstorms usually appear over Portland from February to November.
The weather data here are long-term averages provided by the US National Centers for Environmental Information (NCEI). Temperature and precipitation are 1991-2020 normals while humidity and thunderstorms are 1961-1990 normals.