December weather - Winter 2024

Weather in December
Frequently asked questions
Average temperature in December
Average pressure in December
Average wind speed in December
Average humidity in December
Average rainfall in December
Average rainfall days in December
Average snowfall in December
Average snowfall days in December
Average daylight in December
Average sunshine in December
Average sunshine days in December
Average UV index in December
Average cloud cover in December
Average visibility in December

Dense pine tree cover and houses in the town of Sammamish, Washington, in the Pine Lake area

Weather in December

December marks the pinnacle of winter in Sammamish, characterised by the year’s lowest average temperature, falling to 33.6°F (0.9°C). The season brings forth a mild amount of snowfall, with the city receiving 0.35" (9mm) in December, creating a white winter spectacle. The increase in relative humidity to 85% indicates higher moisture content in the atmosphere, in line with the winter season. The daylight hours are at their shortest in December, while the pressure reaches its yearly peak of 30.09 in. Despite the cold, the festive spirit of the city sparkles through making it a prime attraction for holiday travelers.

Temperature

Sammamish's December weather, marked by an average high temperature of 42.3°F (5.7°C) and an average low temperature of 33.6°F (0.9°C), is the coldest in the year.

Humidity

January, February and December, with an average relative humidity of 85%, are the most humid months.

Rainfall

December is the month with the most rainfall. Rain falls for 14.1 days and accumulates 1.85" (47mm) of precipitation.

Snowfall

January through April, November and December are months with snowfall. In December, in Sammamish, it is snowing for 1.3 days. Throughout December, 0.35" (9mm) of snow is accumulated. In Sammamish, during the entire year, snow falls for 9.3 days and aggregates up to 3.27" (83mm) of snow.

Daylight

The month with the shortest days in Sammamish is December, with an average of 8h and 30min of daylight.
On the first day of the month, sunrise is at 7:36 am and sunset at 4:18 pm. On the last day of December, in Sammamish, Washington, sunrise is at 7:56 am and sunset at 4:26 pm PST.

Sunshine

The months with the least sunshine are January and December, with an average of 4.2h of sunshine.

UV index

January, February, November and December, with an average maximum UV index of 2, are months with the lowest UV index. A UV Index estimate of 2, and below, represents a low threat to health from exposure to the Sun's UV rays for ordinary individuals.
Note: The maximum daily UV index, 2 in December, converts into the following recommendations:
Prolonged sun exposure generally does not trouble most people. However, it is vital to ensure protection for babies, children, and individuals with sensitive skin. Considering the Sun's intensity during midday, it's wise to minimize direct exposure. A hat with a generous brim can prevent nearly 50% of UV rays from reaching your eyes. Take heed! The reflection of snow can intensify the Sun's UV radiation nearly double.

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Frequently asked questions

What month is the coldest in Sammamish?

Temperature readings reach their annual highs in December, averaging 42.3°F (5.7°C) and a minimum average of 33.6°F (0.9°C).

How cold is December in Sammamish?

December temperatures in Sammamish, Washington, vary between a high-temperature of 42.3°F (5.7°C) and a low-temperature of 33.6°F (0.9°C).

What are the most humid months in Sammamish?

The months with the highest humidity in Sammamish are January, February and December, with an average relative humidity of 85%.

What is the average humidity in December in Sammamish?

In Sammamish, the average relative humidity in December is 85%.

What is the wettest month in Sammamish?

December is the month with the most rainfall. Rain falls for 14.1 days and accumulates 1.85" (47mm) of precipitation.

How many days does it rain in December in Sammamish?

In Sammamish, in December, during 14.1 rainfall days, 1.85" (47mm) of precipitation is typically accumulated.

How much does it snow in Sammamish in December?

In Sammamish, in December, snow falls for 1.3 days, with typically accumulated 0.35" (9mm) of snow.

What is the month with the shortest days in Sammamish?

December has the shortest days of the year in Sammamish, Washington, with an average of 8h and 30min of daylight.

How many hours of daylight does Sammamish have in December?

In December, the average day length in Sammamish, Washington, is 8h and 30min.

When is the sunrise / sunset in December in Sammamish?

On the first day of December in Sammamish, Washington, sunrise is at 7:36 am and sunset at 4:18 pm. On the last day of the month, sunrise is at 7:56 am and sunset at 4:26 pm PST.

What are the months with the least sunshine in Sammamish?

The months with the least sunshine are January and December, with an average of 4.2h of sunshine.

How long on average sun shines in December in Sammamish?

The average sunshine duration in December in Sammamish, Washington, is 4.2h.

What is the month with the lowest UV index in Sammamish?

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

How high is the UV index in December in Sammamish?

The average daily maximum UV index in December in Sammamish is 2. A UV Index reading of 2, and below, represents a minimal hazard to health from unprotected exposure to UV radiation.

Today

Tomorrow

Long-term

Year J F M A M J J A S O N December

Nov

December

Jan

Average high temperature

48.2°F 9°C

42.3°F 5.7°C

44.1°F 6.7°C

Average low temperature

Average pressure

Average wind speed

Average max. wind speed

5.2mph 8.4km/h

5mph 8km/h

5.5mph 8.9km/h

Average wind speed gusts

Average humidity

Average rainfall

Average rainfall days

Average snowfall

Average snowfall days

Average daylight

Average sunshine

Average sunshine days

13.5

15.2

15.8

Average UV index

Average cloud cover

Average visibility

Average temperature in December
Sammamish, WA

Average high temperature in December: 42.3°F

The warmest month (with the highest average high temperature) is August (76.5°F).
The month with the lowest average high temperature is December (42.3°F).

Average low temperature in December: 33.6°F

The month with the highest average low temperature is August (52.2°F).
The coldest month (with the lowest average low temperature) is December (33.6°F).

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Average pressure in December
Sammamish, 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
Sammamish, WA

Average wind speed in December: 4.6mph

The windiest month (with the highest average wind speed) is January (5mph).
The calmest month (with the lowest average wind speed) is August (3.4mph).

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Average humidity in December
Sammamish, WA

Average humidity in December: 85%

The months with the highest relative humidity are January, February and December (85%).
The month with the lowest relative humidity is July (70%).

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Average rainfall in December
Sammamish, WA

Average rainfall in December: 1.85"

The wettest month (with the highest rainfall) is December (1.85").
The driest months (with the least rainfall) are July and August (0.35").

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Average rainfall days in December
Sammamish, WA

Average rainfall days in December: 14.1 days

The month with the highest number of rainy days is March (14.8 days).
The month with the least rainy days is August (5.2 days).

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Average snowfall in December
Sammamish, WA

Average snowfall in December: 0.35"

The month with the highest snowfall is February (1.38").
The months with the least snowfall are May, June, July, August, September and October (0").

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Average snowfall days in December
Sammamish, WA

Average snowfall days in December: 1.3 days

The month with the highest number of snowfall days is February (3.2 days).
The months with the least snowfall days are May, June, July, August and October (0 days).

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Average daylight in December /
Average sunshine in December
Sammamish, WA

Average daylight in December: 8h and 3min

The month with the longest days is June (Average daylight: 15h and 54min).
The month with the shortest days is December (Average daylight: 8h and 30min).

Average sunshine in December: 4h and 1min

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

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Average sunshine days in December
Sammamish, WA

Average sunshine days in December: 15.2 days

The month with the most sunshine days is August (24 days).
The month with the least sunshine days is November (13.5 days).

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Average UV index in December
Sammamish, WA

Average UV index in December: 2

The months with the highest UV index are June and 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
Sammamish, WA

Average cloud cover in December: 57

The month with the most cloud cover is December (Cloud cover 57).
The month with the least cloud cover is August (Cloud cover 26).

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Average visibility in December
Sammamish, WA

Average visibility in December: 5mi

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

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December weather forecast
Sammamish, WA

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