August weather forecast
Portland, OR

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A colorful autumn view of the outline of Portland City, Oregon, USA
A colorful autumn view of the outline of Portland City, Oregon, USA

Weather in August

In August, Portland's weather remains warm and dry with the least cloud cover. As summer reaches its zenith, the city experiences the second-highest temperature of the season. However, August is also a month to enjoy a palette of vibrant sunset hues. The heat combines with reduced wind speeds, encouraging outdoor activities, picnics, and barbecues. As summer winds down, residents start preparing for the pleasant fall season.

Temperature

August temperatures tend to peak at an average high of 81.5°F (27.5°C) and dip to a low of 55°F (12.8°C).

Heat index

August's mean heat index is appraised at 84.2°F (29°C). A sense of exhaustion might occur with extended exposure and activity, potentially causing heat cramps.
Heat index details are generally centered around shaded locations and a mild breeze. In the presence of direct sunshine, the heat index could be augmented by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature' or 'felt air temperature', is a numerical representation of warmth when taking temperature and moisture levels into account. Physical activity, clothing, and metabolic variations are additional factors that impact an individual's perception of temperature. One's exposure to direct sunlight has the potential to intensify the heat sensation, increasing the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are highly critical for babies and toddlers. Children frequently underestimate the necessity to rest and hydrate. Thirst is a late sign of dehydration - thus, it is vital to stay hydrated, particularly during lengthy physical exercises.

Humidity

August is the least humid month, with an average relative humidity of 63%.

Rainfall

In Portland, in August, it is raining for 5.2 days, with typically 0.39" (10mm) of accumulated precipitation. In Portland, during the entire year, the rain falls for 173.1 days and collects up to 31.18" (792mm) of precipitation.

Snowfall

April through October are months without snowfall.

Daylight

In Portland, the average length of the day in August is 14h and 3min.
On the first day of the month, sunrise is at 5:55 am and sunset at 8:38 pm. On the last day of August, sunrise is at 6:31 am and sunset at 7:49 pm PDT.

Sunshine

With an average of 10.9h of sunshine, August has the most sunshine of the year.

UV index

The average daily maximum UV index in August is 5. A UV Index value of 3 to 5 symbolizes a moderate threat to health from unprotected exposure to Sun's UV rays for the ordinary person.
Note: In August, the maximum UV index of 5 transforms into these recommendations:
Take precautions - Protection against skin and eye damage is obliged. The Sun is at its harshest during midday; protect yourself by staying in shaded areas and minimizing exposure. Combat UV radiation's detrimental effects with sun-safe clothing and UV-blocking eyewear.

Frequently asked questions

What is the warmest month?

August, characterized by an average high temperature of 81.5°F (27.5°C) and a low temperature of 55°F (12.8°C), is generally the warmest month.

What is the average August temperature?

During August, Portland experiences an average high-temperature of 81.5°F (27.5°C) and a low-temperature of 55°F (12.8°C). In August, the average heat index (a.k.a. 'felt air temperature', 'apparent temperature'), which represents the influence of relative humidity on air temperature, is appraised at 84.2°F (29°C).

What is the least humid month?

The least humid month is August, with an average relative humidity of 63%.

What is the average humidity in August?

The average relative humidity in August is 63%.

How many days does it rain in August?

In August, the rain falls for 5.2 days. Throughout August, 0.39" (10mm) of precipitation is accumulated.

When it does not snow?

In Portland, snow does not fall in April through October.

How many hours of daylight does Portland have in August?

In August, the average day length is 14h and 3min.

When is the sunrise / sunset in August?

On the first day of August, sunrise is at 5:55 am and sunset at 8:38 pm. On the last day of the month, sunrise is at 6:31 am and sunset at 7:49 pm PDT.

What month has the most sunshine?

The month with the most sunshine is August, with an average of 10.9h of sunshine.

How many hours of sunshine does Portland have in August?

The average sunshine duration in August is 10.9h.

What is the UV index intensity in August?

The average daily maximum UV index in August is 5. A UV Index of 3 to 5 symbolizes a moderate vulnerability from unsafe exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in August
Portland, OR

Average temperature in August - Portland, OR
  • Average high temperature in August: 81.5°F

The warmest month (with the highest average high temperature) is August (81.5°F).
The month with the lowest average high temperature is December (44.1°F).

  • Average low temperature in August: 55°F

The month with the highest average low temperature is August (55°F).
The coldest month (with the lowest average low temperature) is December (34.7°F).

Average pressure in August
Portland, OR

Average pressure in August - Portland, OR
  • Average pressure in August: 30"Hg

The month with the highest atmospheric pressure is January (30.12"Hg).
The month with the lowest atmospheric pressure is August (30"Hg).

Average wind speed in August
Portland, OR

Average wind speed in August - Portland, OR
  • Average wind speed in August: 3.9mph

The windiest month (with the highest average wind speed) is January (5.8mph).
The calmest month (with the lowest average wind speed) is August (3.9mph).

Average humidity in August
Portland, OR

Average humidity in August - Portland, OR
  • Average humidity in August: 63%

The months with the highest relative humidity are January, February and December (83%).
The month with the lowest relative humidity is August (63%).

Average rainfall in August
Portland, OR

Average rainfall in August - Portland, OR
  • Average rainfall in August: 0.39"

The wettest month (with the highest rainfall) is December (4.53").
The driest month (with the least rainfall) is July (0.31").

Average rainfall days in August
Portland, OR

Average rainfall days in August - Portland, OR
  • Average rainfall days in August: 5.2 days

The month with the highest number of rainy days is March (20.4 days).
The month with the least rainy days is July (4.9 days).

Average snowfall in August
Portland, OR

Average snowfall in August - Portland, OR
  • Average snowfall in August: 0"

The month with the highest snowfall is March (1.5").
The months with the least snowfall are April, May, June, July, August, September and October (0").

Average snowfall days in August
Portland, OR

Average snowfall days in August - Portland, OR
  • Average snowfall days in August: 0 days

The month with the highest number of snowfall days is February (2.3 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).

Average daylight in August /
Average sunshine in August
Portland, OR

Average daylight in August / Average sunshine in August - Portland, OR
  • Average daylight in August: 14h and 1min

The month with the longest days is June (Average daylight: 15h and 36min).
The month with the shortest days is December (Average daylight: 8h and 48min).

  • Average sunshine in August: 10h and 5min

The month with the most sunshine is August (Average sunshine: 10h and 54min).
The month with the least sunshine is January (Average sunshine: 4h and 6min).

Average sunshine days in August
Portland, OR

Average sunshine days in August - Portland, OR
  • Average sunshine days in August: 23.8 days

The months with the most sunshine days are July and August (23.8 days).
The month with the least sunshine days is March (8.3 days).

Average UV index in August
Portland, OR

Average UV index in August - Portland, OR
  • Average UV index in August: 5

The month with the highest UV index is July (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).

Average cloud cover in August
Portland, OR

Average cloud cover in August - Portland, OR
  • Average cloud cover in August: 23

The month with the most cloud cover is February (Cloud cover 58).
The month with the least cloud cover is August (Cloud cover 23).

Average visibility in August
Portland, OR

Average visibility in August - Portland, OR
  • Average visibility in August: 6mi

The months with the highest visibility are July, August and September (6mi).
The months with the lowest visibility are January, February, March, April, May, June, October, November and December (5mi).

Portland, Oregon, USA

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