Portland Weather in August

August's pleasantly hot temperatures coupled with sunny, dry skies make for excellent summer weather in Portland, Oregon. Temperatures this month are not much different from the previous one.

This page gives detailed information on the typical August temperature, precipitation, sun, humidity, wind and storms 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.

Temperature Weather iconTemperature

82 °F August average high 28 °C
57 °F August average low 14 °C

The years hottest days spill over from July into the first week of August. From the 1st to 8th daily highs average 83 degrees Fahrenheit (28 degrees Celsius) and lows are 58 °F (14 °C).

19 days 80 °F max. or more (27 °C)
25 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 6 days this month when the thermometer reaches into the 90s °F (over 32 °C). A day as hot as 100 °F (38 °C) can appear now, but that doesn't happen every August.

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

Rainy Weather iconRain

0.6 in total precipitation 16 mm
4 days of rain

Half the time, Portland receives 0.1 to 0.9 inches (2 to 22 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.


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.

Portland Weather
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