August weather forecast
Mercer Island, WA

Weather in August

August, the last month of the summer in Mercer Island, is also a moderately hot month, with temperature in the range of an average high of 76.6°F (24.8°C) and an average low of 53.4°F (11.9°C).

Temperature

August is the warmest month, with an average high-temperature of 76.6°F (24.8°C) and an average low-temperature of 53.4°F (11.9°C).

Humidity

In Mercer Island, the average relative humidity in August is 70%.

Rainfall

In Mercer Island, during 4.1 rainfall days, 0.31" (8mm) of precipitation is typically accumulated. In Mercer Island, during the entire year, the rain falls for 119.1 days and collects up to 11.97" (304mm) of precipitation.

Snowfall

April through October are months without snowfall in Mercer Island.

Daylight

The average length of the day in August in Mercer Island is 14h and 12min.
On the first day of August, sunrise is at 5:46 am and sunset at 8:43 pm. On the last day of the month, sunrise is at 6:26 am and sunset at 7:51 pm PDT.

Sunshine

With an average of 10.7h of sunshine, August has the most sunshine of the year.

UV index

The average daily maximum UV index in August is 4. A UV Index estimate of 3 to 5 represents a medium vulnerability from unsafe exposure to UV radiation for average individuals.
Note: The average daily UV index of 4 in August transform into the following instructions:
Take precautions - Protection against sunburn is recommended. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes.
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FAQ

What is the warmest month in Mercer Island?

With an average high-temperature of 76.6°F (24.8°C) and an average low-temperature of 53.4°F (11.9°C), August is the warmest month in Mercer Island, Washington.

What is the temperature in August in Mercer Island?

In Mercer Island, in August, the average high-temperature is 76.6°F (24.8°C), and the average low-temperature is 53.4°F (11.9°C).

What is the average humidity in August in Mercer Island?

In Mercer Island, Washington, the average relative humidity in August is 70%.

How many days does it rain in August in Mercer Island?

In Mercer Island, in August, it is raining for 4.1 days, with typically 0.31" (8mm) of accumulated precipitation.

When it does not snow in Mercer Island?

April through October are months without snowfall in Mercer Island.

What is the average length of the day in August in Mercer Island?

In August, the average day length is 14h and 12min.

When are sunrise and sunset in August in Mercer Island?

In August, on the first day of the month, sunrise is at 5:46 am and sunset at 8:43 pm. On the last day of the month, in Mercer Island, sunrise is at 6:26 am and sunset at 7:51 pm PDT.

What month has the most sunshine in Mercer Island?

The month with the most sunshine in Mercer Island is August, with an average of 10.7h of sunshine.

How many hours of sunshine does Mercer Island have in August?

In Mercer Island, Washington, the average sunshine duration in August is 10.7h.

What is the UV index intensity in August in Mercer Island?

In August, the average daily maximum UV index in Mercer Island is 4. A UV Index of 3 to 5 symbolizes a medium health risk from unsafe exposure to Sun's UV rays.
Average wind speed gusts
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in August
Mercer Island, WA

Average temperature in August - Mercer Island, WA
  • Average high temperature in August: 76.6°F

The warmest month (with the highest average high temperature) is August (76.6°F).
The month with the lowest average high temperature is December (42.8°F).

  • Average low temperature in August: 53.4°F

The month with the highest average low temperature is August (53.4°F).
The coldest month (with the lowest average low temperature) is February (34.5°F).

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Average pressure in August
Mercer Island, WA

Average pressure in August - Mercer Island, WA
  • Average pressure in August: 30"Hg

The month with the highest atmospheric pressure is January (30.1"Hg).
The month with the lowest atmospheric pressure is August (30"Hg).

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Average wind speed in August
Mercer Island, WA

Average wind speed in August - Mercer Island, WA
  • Average wind speed in August: 3.4mph

The windiest month (with the highest average wind speed) is March (5.1mph).
The calmest month (with the lowest average wind speed) is August (3.4mph).

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Average humidity in August
Mercer Island, WA

Average humidity in August - Mercer Island, WA
  • Average humidity in August: 70%

The month with the highest relative humidity is January (85%).
The month with the lowest relative humidity is July (69%).

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Average rainfall in August
Mercer Island, WA

Average rainfall in August - Mercer Island, WA
  • Average rainfall in August: 0.31"

The wettest month (with the highest rainfall) is December (2.01").
The driest month (with the least rainfall) is July (0.24").

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Average rainfall days in August
Mercer Island, WA

Average rainfall days in August - Mercer Island, WA
  • Average rainfall days in August: 4.1 days

The month with the highest number of rainy days is March (13.7 days).
The month with the least rainy days is August (4.1 days).

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Average snowfall in August
Mercer Island, WA

Average snowfall in August - Mercer Island, WA
  • Average snowfall in August: 0"

The month with the highest snowfall is February (1.77").
The months with the least snowfall are April, May, June, July, August, September and October (0").

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Average snowfall days in August
Mercer Island, WA

Average snowfall days in August - Mercer Island, WA
  • Average snowfall days in August: 0 days

The month with the highest number of snowfall days is February (3 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).

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Average daylight in August /
Average sunshine in August
Mercer Island, WA

Average daylight in August / Average sunshine in August - Mercer Island, WA
  • Average daylight in August: 14h and 12min

The month with the longest days is June (Average daylight: 15h and 55min).
The month with the shortest days is December (Average daylight: 8h and 31min).

  • Average sunshine in August: 10h and 42min

The month with the most sunshine is August (Average sunshine: 10h and 42min).
The month with the least sunshine is December (Average sunshine: 4h and 12min).

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Average sunshine days in August
Mercer Island, WA

Average sunshine days in August - Mercer Island, WA
  • Average sunshine days in August: 24.9 days

The month with the most sunshine days is August (24.9 days).
The month with the least sunshine days is February (13.8 days).

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Average UV index in August
Mercer Island, WA

Average UV index in August - Mercer Island, WA
  • Average UV index in August: 4

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).

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Average cloud cover in August
Mercer Island, WA

Average cloud cover in August - Mercer Island, WA
  • Average cloud cover in August: 25

The month with the most cloud cover is December (Cloud cover 56).
The month with the least cloud cover is August (Cloud cover 25).

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Average visibility in August
Mercer Island, WA

Average visibility in August - Mercer Island, WA
  • Average visibility in August: 6mi

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

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