December weather forecast
Issaquah, WA

Weather in December

December, the first month of the winter in Issaquah, is also a wintry month, with an average temperature varying between 42.3°F (5.7°C) and 33.4°F (0.8°C).

Temperature

The coldest month is December, with an average high-temperature of 42.3°F (5.7°C) and an average low-temperature of 33.4°F (0.8°C).

Humidity

In Issaquah, the average relative humidity in December is 84%.

Rainfall

December is the month with the most rainfall in Issaquah, Washington. Rain falls for 13.7 days and accumulates 2.01" (51mm) of precipitation.

Snowfall

Months with snowfall are January through April, November and December. In Issaquah, Washington, during December, snow falls for 0.8 days and regularly aggregates up to 0.16" (4mm) of snow. In Issaquah, during the entire year, snow falls for 5.9 days and aggregates up to 1.93" (49mm) of snow.

Daylight

The month with the shortest days in Issaquah is December, with an average of 8h and 31min of daylight.
On the first day of the month, sunrise is at 7:35 am and sunset at 4:19 pm. On the last day of December, sunrise is at 7:55 am and sunset at 4:26 pm PST.

Sunshine

December has the least sunshine of the year in Issaquah, Washington, with an average of 4h of sunshine.

UV index

The months with the lowest UV index in Issaquah are January, February, November and December, with an average maximum UV index of 2. A UV Index of 2, and less, symbolizes a low health risk from unsafe exposure to UV radiation for the ordinary person.
Note: The average daily UV index of 2 in December transform into the following instructions:
Most people can stay in the Sun for up to 1 hour without burning, apart from children that always must be protected from sun exposure. 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. Beware! The strength of the UV rays is increased nearly double-fold by the reflection of the snow.
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FAQ

What is the coldest month in Issaquah?

The coldest month in Issaquah, Washington, is December, with an average high-temperature of 42.3°F (5.7°C) and an average low-temperature of 33.4°F (0.8°C).

What is the temperature in December in Issaquah?

In Issaquah, Washington, in December, the average high-temperature is 42.3°F (5.7°C), and the average low-temperature is 33.4°F (0.8°C).

What is the average humidity in December in Issaquah?

In Issaquah, the average relative humidity in December is 84%.

What is the wettest month in Issaquah?

The month with the most rainfall in Issaquah is December, when the rain falls for 13.7 days and typically aggregates up to 2.01" (51mm) of precipitation.

How much does it rain in Issaquah in December?

In Issaquah, Washington, during December, the rain falls for 13.7 days and regularly aggregates up to 2.01" (51mm) of precipitation.

How much does it snow in Issaquah in December?

In Issaquah, during December, snow falls for 0.8 days and regularly aggregates up to 0.16" (4mm) of snow.

What is the month with the shortest days in Issaquah?

With an average of 8h and 31min of daylight, December has the shortest days of the year.

How many hours of daylight does Issaquah have in December?

The average day length in December is 8h and 31min.

When are sunrise and sunset in December in Issaquah?

In December, on the first day of the month, sunrise is at 7:35 am and sunset at 4:19 pm. On the last day of the month, in Issaquah, sunrise is at 7:55 am and sunset at 4:26 pm PST.

What is the month with the least sunshine in Issaquah?

December has the least sunshine of the year in Issaquah, with an average of 4h of sunshine.

How many hours of sunshine does Issaquah have in December?

In Issaquah, the average sunshine duration in December is 4h.

When is the lowest UV index in Issaquah?

January, February, November and December, with an average maximum UV index of 2, are months with the lowest UV index in Issaquah, Washington.

What is the UV index reading in December in Issaquah?

In Issaquah, Washington, the average daily maximum UV index in December is 2. A UV Index value of 2, and less, symbolizes a low health threat from exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in December
Issaquah, WA

Average temperature in December - Issaquah, WA
  • Average high temperature in December: 42.3°F

The warmest month (with the highest average high temperature) is August (77°F).
The month with the lowest average high temperature is December (42.3°F).

  • Average low temperature in December: 33.4°F

The month with the highest average low temperature is August (51.4°F).
The coldest months (with the lowest average low temperature) are February and December (33.4°F).

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Average pressure in December
Issaquah, WA

Average pressure in December - Issaquah, WA
  • Average pressure in December: 30.09"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 December
Issaquah, WA

Average wind speed in December - Issaquah, WA
  • Average wind speed in December: 4.7mph

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

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Average humidity in December
Issaquah, WA

Average humidity in December - Issaquah, WA
  • Average humidity in December: 84%

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

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Average rainfall in December
Issaquah, WA

Average rainfall in December - Issaquah, WA
  • Average rainfall in December: 2.01"

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 December
Issaquah, WA

Average rainfall days in December - Issaquah, WA
  • Average rainfall days in December: 13.7 days

The month with the highest number of rainy days is March (14.8 days).
The month with the least rainy days is August (4.3 days).

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Average snowfall in December
Issaquah, WA

Average snowfall in December - Issaquah, WA
  • Average snowfall in December: 0.16"

The month with the highest snowfall is February (0.94").
The months with the least snowfall are May, June, July, August, September and October (0").

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Average snowfall days in December
Issaquah, WA

Average snowfall days in December - Issaquah, WA
  • Average snowfall days in December: 0.8 days

The month with the highest number of snowfall days is February (2.5 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 December /
Average sunshine in December
Issaquah, WA

Average daylight in December / Average sunshine in December - Issaquah, WA
  • Average daylight in December: 8h and 31min

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 December: 4h and 0min

The month with the most sunshine is August (Average sunshine: 10h and 30min).
The month with the least sunshine is December (Average sunshine: 4h and 0min).

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Average sunshine days in December
Issaquah, WA

Average sunshine days in December - Issaquah, WA
  • Average sunshine days in December: 14.8 days

The month with the most sunshine days is August (25 days).
The month with the least sunshine days is February (12.9 days).

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Average UV index in December
Issaquah, WA

Average UV index in December - Issaquah, WA
  • Average UV index in December: 2

The month with the highest UV index is July (UV index 5).
The months with the lowest UV index are January, February, November and December (UV index 2).

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Average cloud cover in December
Issaquah, WA

Average cloud cover in December - Issaquah, WA
  • Average cloud cover in December: 58

The months with the most cloud cover are January and December (Cloud cover 58).
The month with the least cloud cover is August (Cloud cover 27).

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Average visibility in December
Issaquah, WA

Average visibility in December - Issaquah, WA
  • Average visibility in December: 4mi

The months with the highest visibility are July and August (6mi).
The months with the lowest visibility are January, February and December (4mi).

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