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August Weather in Portland, United States

Last updated: June 24, 2025

In Portland, United States, the average temperature in August hovers around 21°C (70°F), with delightful peaks reaching up to 33°C (91°F) and cooler dips as low as 10°C (50°F). Expect around 112 mm (4.4 in) of precipitation over 11 days, contributing to the area's average humidity of 69%. Enjoy the balanced climate this month!

August Temperature in Portland

In August in Portland, the average temperature is 21°C (70°F), with maximums reaching 33°C (91°F) and minimums dipping as low as 10°C (50°F). This makes it an ideal time for travelers seeking pleasant weather and a variety of outdoor activities.

August Weather in Portland: Daily Temperature Highs, Lows, and Averages

The chart illustrates August temperature patterns in Portland, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Portland, August typically has an average temperature of 21°C (70°F), with highs reaching up to 33°C (91°F) and lows dropping to around 10°C (50°F).
JanFebMarAprMayJunJulAugSepOctNovDec192135455970737064493527
Data source: Temperature data for Portland generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

August Precipitation in Portland

In Portland in August, the precipitation amount is 112 mm (4.4 in) that occurs over the course of 11 days.

August Precipitation Trends in Portland

The chart displays monthly precipitation patterns in Portland, with values for each month alongside August’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how August’s conditions compare to those of other months. In Portland, August typically receives around 112 mm (4.4 inches) of precipitation spread over approximately 11 days.
JanFebMarAprMayJunJulAugSepOctNovDec385460921391241121121111195344
Data source: Precipitation data for August generated using information from the Copernicus Climate Change Service.
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August Humidity in Portland

In Portland in August humidity is 69%. With an average temperature of 21°C (70°F), this humidity feels like a warm embrace, making outdoor activities enjoyable but requiring occasional breaks for hydration and shade during your travels.

August Average Humidity in Portland

This chart illustrates the average monthly humidity levels in Portland, with August’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In August, average humidity in Portland is approximately 69%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec84%85%84%83%75%79%75%69%74%79%88%82%
Data source: Humidity data for August generated using information from the Copernicus Climate Change Service.

August UV Index in Portland

In Portland in August, the maximum UV index is 9, which corresponds to a very high Exposure Category. The time to burn is just 15 minutes, so it's essential to take precautions. For detailed information, you can check the Hourly UV Index in Portland.

Maximum UV Index Levels in Portland for August

The chart shows the monthly maximum UV Index (UVI) for Portland in August, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In August, the maximum UV index in Portland typically reaches 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec24589101098532
Data source: Portland August UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

How August Weather in Portland Compares to Other Months

Weather in Portland varies notably across the year, with each month offering distinct climate conditions. This page compares August’s weather to other months in Portland, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Portland, showing how August’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-7°C (20°F)38 mm (1.5 inches)84%low
February Weather-6°C (21°F)54 mm (2.1 inches)85%moderate
March Weather2°C (35°F)60 mm (2.3 inches)84%moderate
April Weather7°C (45°F)92 mm (3.6 inches)83%very high
May Weather15°C (59°F)139 mm (5.5 inches)75%very high
June Weather21°C (70°F)124 mm (4.9 inches)79%very high
July Weather23°C (74°F)112 mm (4.4 inches)75%very high
August Weather21°C (70°F)112 mm (4.4 inches)69%very high
September Weather18°C (64°F)111 mm (4.4 inches)74%very high
October Weather10°C (50°F)119 mm (4.7 inches)79%moderate
November Weather1°C (35°F)53 mm (2.1 inches)88%moderate
December Weather-3°C (27°F)44 mm (1.7 inches)82%low

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