August Weather in Portland, United States

Last updated: June 24, 2025

In August, the average temperature in Portland, United States is a pleasant 20°C (68°F), making it an ideal time to explore. Expect a minimum of 7°C (45°F) and a maximum of 35°C (95°F), providing a diverse range of weather. With about 81 mm (3.2 in) of precipitation over 10 days, it’s wise to pack an umbrella. The air is comfortably humid, with an average humidity of 78%, adding to the region's unique charm.

August Temperature in Portland

In August in Portland, the average temperature is 20°C (68°F). Maximums can reach 35°C (95°F), while minimums can be as low as 7°C (45°F). This varied climate makes Portland an ideal destination for travelers seeking both warm days and cooler evenings.

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 20°C (68°F), with highs reaching up to 35°C (95°F) and lows dropping to around 7°C (45°F).

Data source: Temperature data for Portland generated using information from the Copernicus Climate Change Service.

August Precipitation in Portland

In Portland in August, the precipitation amount is 81 mm (3.2 in) over a span of 10 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 81 mm (3.2 inches) of precipitation spread over approximately 10 days.

Data source: Precipitation data for August generated using information from the Copernicus Climate Change Service.

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Millimeters (mm) Inches (in)

August Humidity in Portland

In Portland in August humidity is 78%. With an average temperature of 20°C (68°F), this humidity feels like a warm, enveloping blanket that makes exploring the sights a bit sticky, so travelers should stay hydrated and take frequent breaks in the shade.

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 78%, offering insight into how humid the weather typically is during this month.

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 8, which corresponds to a very high Exposure Category. This means that the time to burn is only 15 minutes. For more detailed information, you can refer to 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 8, which falls under the very high exposure category.

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.
	Temperature	Precipitation	Humidity	UV
January Weather	-12°C (10°F)	18 mm (0.7 inches)	90%	low
February Weather	-13°C (9°F)	19 mm (0.8 inches)	92%	moderate
March Weather	-3°C (27°F)	27 mm (1.1 inches)	85%	moderate
April Weather	4°C (39°F)	41 mm (1.6 inches)	81%	high
May Weather	13°C (56°F)	55 mm (2.2 inches)	75%	very high
June Weather	20°C (69°F)	91 mm (3.6 inches)	79%	very high
July Weather	22°C (72°F)	62 mm (2.4 inches)	76%	very high
August Weather	20°C (68°F)	81 mm (3.2 inches)	78%	very high
September Weather	15°C (60°F)	68 mm (2.7 inches)	77%	high
October Weather	6°C (44°F)	79 mm (3.1 inches)	79%	moderate
November Weather	-2°C (28°F)	21 mm (0.8 inches)	86%	moderate
December Weather	-8°C (18°F)	39 mm (1.5 inches)	86%	low