Portland Weather in August

August's pleasantly hot temperatures coupled with sunny, dry skies make for excellent summer weather in Portland, Oregon. This is the city's hottest month, although it is only a little warmer on average than the previous one.

This page gives detailed information on the typical August weather for Portland.

You can jump directly to data and descriptions for:

The numbers here are historical averages based on climate data gathered near the Portland International Airport, located a few miles from downtown Portland.

Temperature Weather iconTemperature

81 °F August average high 27 °C
57 °F August average low 14 °C

In most years, Portland averages a daily maximum temperature for August that's between 78 and 84 degrees Fahrenheit (26 to 29 degrees Celsius). The minimum temperature usually falls between 55 and 58 °F (13 to 15 °C).

August is Portland's hottest month overall. But the days at Portland begin to cool during August. By the end of the month, the temperature has dropped around 3 °F (2 °C) below what it was at the start.

16 days 80 °F max. or more (27 °C)
26 days 60 °F min. or less (16 °C)

Nearly every day in August warms to over 70 °F (21 °C) in Portland. The city averages 5 days this month when the thermometer reaches into the 90s °F (over 32 °C). A temperature as hot as 100 °F (38 °C) occurs here only once a decade during August.

At night, the thermometer dips just once on average to 50 °F (10 °C) or below. But August does not normally get as cold as 40 °F (4 °C).

Rainy Weather iconRain

0.8 in total precipitation 20 mm
4 days of rain

Half the time, Portland receives 0.1 to 1.2 inches (3 to 29 mm) of rainfall in August. One in four years has drier weather, while another one in four is wetter.

Sunny Weather iconSun

66 % sunshine
11 days clear skies

The sun's rays reach the ground in Portland during 66 percent of daylight hours on average in August, for a total of 287 hours in the month. Typically on 11 days this month the sky is mainly clear, with at most 30 percent cloud cover.

Sunlight in August at Portland lasts for 14 hours and 2 minutes a day on average. The longest day of the month is the 1st with 14 hours and 43 minutes of daylight. By the end of the month, the days have shortened to 13:18 from sunrise to sunset. These durations can vary by a minute or two from year to year.

Humid Weather iconHumidity

65 % August average humidity

The relative humidity in Portland during August usually peaks at 82 percent in the morning then drops to 44 percent by mid afternoon.

Local Time1 am4 am7 am10 am1 pm4 pm7 pm10 pm
Humidity % 77 82 81 64 49 44 54 68

Windy Weather iconWind

7.1 mph August wind speed average 11.4 kph

August is a little less windy than most other months in Portland.

Stormy Weather iconStorms

0 days rainfall of 0.5 inches (13 mm) or more
1 day with thunderstorms in August

Every few years, Portland does get half an inch (13 mm) or more of rain in one day during August.


These weather data are long-term historical averages provided by the National Climatic Data Center of the United States. The temperature and precipitation numbers are 1981-2010 normals while the humidity and thunderstorm statistics are 1961-1990 normals.

Portland Weather
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