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August Weather in Portland, United States

Last updated: June 24, 2025

In August, the average temperature in Portland, United States hovers around 25°C (78°F), with extremes ranging from a refreshing 14°C (57°F) to a sweltering 36°C (98°F). Visitors can expect about 124 mm (4.9 in) of precipitation spread over 14 days, contributing to an average humidity of 74%. Enjoy the vibrant climate while planning your activities!

August Temperature in Portland

In August in Portland, the average temperature is 25°C (78°F). The maximum can reach 36°C (98°F) and the minimum can be as low as 14°C (57°F). This mild climate makes Portland an ideal destination for travelers looking to enjoy pleasant weather and 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 25°C (78°F), with highs reaching up to 36°C (98°F) and lows dropping to around 14°C (57°F).
JanFebMarAprMayJunJulAugSepOctNovDec404452597076807873634845
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 124 mm (4.9 in) over a span of 14 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 124 mm (4.9 inches) of precipitation spread over approximately 14 days.
JanFebMarAprMayJunJulAugSepOctNovDec10518515715012214112512412513888147
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 74%. With an average temperature of 25°C (78°F), this humidity feels like you're enveloped in a warm, thick blanket, making outdoor activities feel more strenuous and necessitating frequent breaks and hydration for comfortable travel.

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 74%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec87%86%86%82%83%83%80%74%71%78%88%88%
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 reaches 10, which corresponds to a very high Exposure Category. With a time to burn of just 15 minutes, it's crucial to take precautions. For more 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 10, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec36710101111109753
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 Weather4°C (40°F)105 mm (4.1 inches)87%moderate
February Weather7°C (44°F)185 mm (7.3 inches)86%high
March Weather11°C (52°F)157 mm (6.2 inches)86%high
April Weather15°C (59°F)150 mm (5.9 inches)82%very high
May Weather21°C (70°F)122 mm (4.8 inches)82%very high
June Weather25°C (77°F)141 mm (5.5 inches)83%extreme
July Weather27°C (80°F)125 mm (4.9 inches)80%extreme
August Weather25°C (78°F)124 mm (4.9 inches)74%very high
September Weather23°C (74°F)125 mm (4.9 inches)71%very high
October Weather17°C (63°F)138 mm (5.4 inches)78%high
November Weather9°C (48°F)88 mm (3.4 inches)88%moderate
December Weather7°C (45°F)147 mm (5.8 inches)88%moderate

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