August weather forecast and climate
Seattle, WA

Beautiful dusk skyline over the giant skyscrapers of Seattle, Washington
Beautiful dusk skyline over the giant skyscrapers of Seattle, Washington
August remains moderately warm and pleasant with the temperatures in the range of 55.4°F (13°C) and 73.4°F (23°C), but witnesses significant rise in humidity to 68%. This weather is the best for all outdoor activities as it remains moderately rainy with only six days of rainfall all August to collect only 1.3" (33mm) of precipitation.
The ocean temperatures remain steady at 57.2°F (14°C), making the waters inviting for a swim and later on a bask in the nine hours of warm sunshine. Night temperatures remain tolerable, and most visitors enjoy the night festivals like the Seattle International Beerfest.

What is the warmest month in Seattle?

With an average high-temperature of 76.3°F (24.6°C) and an average low-temperature of 55.9°F (13.3°C), August is the warmest month in Seattle, Washington.

What is the temperature in August in Seattle?

The average high-temperature, in August, in Seattle, Washington, is 76.3°F (24.6°C), while the average low-temperature is 55.9°F (13.3°C).

How many days does it rain in August in Seattle?

In Seattle, in August, during 4.8 rainfall days, typically, 0.9" (22.4mm) of precipitation is accumulated.

When is the sea warmest in Seattle?

August is the month with the warmest seawater, with an average sea temperature of 53.6°F (12°C). Swimming in 53.6°F (12°C) is considered dangerous. Unprotected immersion in temperatures below 50°F (10°C) causes quickly maximum intensity cold shock with hyperventilation.

How cold is the water in August in Seattle?

In Seattle, Washington, in August, the average water temperature is 53.6°F (12°C). At temperatures below 50°F (10°C), swimming in a suitably protected swimsuit is feasible; otherwise, cold shock and loss of breathing control are imminent. Even a short swim, without thermal protection, at temperatures around 55.4°F (13°C) is not comfortable.
Average temperature in August - Seattle, WA
  • Average high temperature in August: 76.3°F

The warmest month (with the highest average high temperature) is August (76.3°F).
The month with the lowest average high temperature is December (45.7°F).

  • Average low temperature in August: 55.9°F

The month with the highest average low temperature is August (55.9°F).
The coldest month (with the lowest average low temperature) is December (35.6°F).

Average humidity in August - Seattle, WA
  • Average humidity in August: 68.2%

The month with the highest relative humidity is December (80.1%).
The month with the lowest relative humidity is July (65.4%).

Average rainfall in August - Seattle, WA
  • Average rainfall in August: 0.9"

The wettest month (with the highest rainfall) is November (6.6").
The driest month (with the lowest rainfall) is July (0.7").

Average rainfall days in August - Seattle, WA
  • Average rainfall days in August: 4.8 days

The month with the highest number of rainy days is November (18.4 days).
The month with the lowest number of rainy days is August (4.8 days).

Average snowfall in August - Seattle, WA
  • Average snowfall in August: 0"

Months with the highest snowfall are February and December (1.7").
Months with the lowest snowfall are April, May, June, July, August, September and October (0").

Average snowfall days in August - Seattle, WA
  • Average snowfall days in August: 0 days

The month with the highest number of snowfall days is December (1.6 days).
Months with the lowest number of snowfall days are April, May, June, July, August, September and October (0 days).

Average sea temperature in August - Seattle, WA
  • Average sea temperature in August: 53.5°F

The best month for swimming (with the highest average sea temperature) is August (53.5°F).
The coldest month (with the lowest average sea temperature) is February (45.3°F).

Average daylight in August / Average sunshine in August - Seattle, WA
  • Average daylight in August: 14.2h

The month with the longest days is June (Average daylight: 15.9h).
The month with shortest days is December (Average daylight: 8.5h).

  • Average sunshine in August: 9.1h

The month with most sunshine is July (Average sunshine: 10.1h).
The month with least sunshine is December (Average sunshine: 1.7h).

Average UV index in August - Seattle, WA
  • Average UV index in August: 6

Months with the highest UV index are June and July (UV index 7).
Months with the lowest UV index are January, November and December (UV index 1).

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