December weather forecast
Fairfax, VA

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Weather in December

As the final month of the year, December takes over in Fairfax, Virginia, with solid winter weather patterns including low temperatures, reduced daylight hours, and increased snowfall. While the month isn’t the coldest, it can offer a significant amount of snowfall with an average of 1.73in. The decline in temperatures, increasing snowfall, dwindling sunshine hours, and rising relative humidity set the stage for a full-fledged winter. These conditions persist as it transitions into the New Year, repeating the annual weather cycle.

Temperature

In December, the meteorological conditions alter, with the average high-temperature shifting from a cool 54.5°F (12.5°C) in November to a frosty 45.5°F (7.5°C). Fairfax temperatures generally rest at a low of 32.9°F (0.5°C) during the December nights.

Humidity

October and December, with an average relative humidity of 77%, are the most humid months.

Rainfall

In Fairfax, in December, during 10.9 rainfall days, 2.72" (69mm) of precipitation is typically accumulated. In Fairfax, during the entire year, the rain falls for 162 days and collects up to 31.65" (804mm) of precipitation.

Snowfall

Months with snowfall are January through April, November and December. In December, it is snowing for 3.1 days. Throughout December, 1.73" (44mm) of snow is accumulated. Throughout the year, in Fairfax, there are 18 snowfall days, and 11.18" (284mm) of snow is accumulated.

Daylight

The month with the shortest days is December, with an average of 9h and 30min of daylight.
On the first day of the month, sunrise is at 7:09 am and sunset at 4:47 pm. On the last day of December, sunrise is at 7:27 am and sunset at 4:57 pm EST.

Sunshine

The months with the least sunshine in Fairfax, Virginia, are January, February and December, with an average of 5.2h of sunshine.

UV index

The months with the lowest UV index in Fairfax, Virginia, are January, February, November and December, with an average maximum UV index of 2. A UV Index of 2, and less, symbolizes a minimal health vulnerability from unprotected exposure to Sun's UV rays for the ordinary person.
Note: A maximum UV index of 2 in December translates into the following recommendations:
Though extended exposure to the sun typically does not concern most people, it is crucial to always shield children, infants, and those with sensitive skin. Being in direct Sun during midday can be harmful due to intense solar radiation; take precautions. For holistic sun protection encompassing the eyes, ears, face, and neck, a wide-brim hat is key. Note this! The Sun's UV radiation can nearly be doubled by the reflection off snow.
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Frequently asked questions

What is the usual temperature for Fairfax in December?

An average high-temperature, in December, in Fairfax, is 45.5°F (7.5°C) and the average low-temperature is 32.9°F (0.5°C). The average heat index (a.k.a. 'felt air temperature', 'apparent temperature'), which combines relative humidity and air temperature, in August is appraised at 95°F (35°C).

What are the most humid months in Fairfax?

The months with the highest humidity in Fairfax, Virginia, are October and December, with an average relative humidity of 77%.

What is the average humidity in December in Fairfax?

The average relative humidity in December is 77%.

How many days does it rain in December in Fairfax?

In Fairfax, in December, during 10.9 rainfall days, 2.72" (69mm) of precipitation is typically accumulated.

How much does it snow in Fairfax in December?

In Fairfax, Virginia, in December, snow falls for 3.1 days, with typically accumulated 1.73" (44mm) of snow.

What is the month with the shortest days in Fairfax?

With an average of 9h and 30min of daylight, December has the shortest days of the year in Fairfax, Virginia.

What is the average length of the day in December in Fairfax?

In Fairfax, the average day length in December is 9h and 30min.

When is the sunrise / sunset in December in Fairfax?

On the first day of December in Fairfax, Virginia, sunrise is at 7:09 am and sunset at 4:47 pm. On the last day of the month, sunrise is at 7:27 am and sunset at 4:57 pm EST.

What is the month with the least sunshine in Fairfax?

January, February and December, with an average of 5.2h of sunshine, are months with the least sunshine.

How many hours of sunshine does Fairfax have in December?

The average sunshine duration in December in Fairfax, Virginia, is 5.2h.

What are the months with the lowest UV index in Fairfax?

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

What is the UV index reading in December in Fairfax?

The average daily maximum UV index in December in Fairfax, Virginia, is 2. A UV Index estimate of 2, and below, represents 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
Fairfax, VA

Average temperature in December - Fairfax, VA
  • Average high temperature in December: 45.5°F

The warmest month (with the highest average high temperature) is July (88°F).
The month with the lowest average high temperature is January (40.5°F).

  • Average low temperature in December: 32.9°F

The month with the highest average low temperature is July (68.4°F).
The coldest month (with the lowest average low temperature) is January (26.4°F).

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Average pressure in December
Fairfax, VA

Average pressure in December - Fairfax, VA
  • Average pressure in December: 30.11"Hg

The month with the highest atmospheric pressure is November (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.95"Hg).

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Average wind speed in December
Fairfax, VA

Average wind speed in December - Fairfax, VA
  • Average wind speed in December: 6.5mph

The windiest month (with the highest average wind speed) is March (7.4mph).
The calmest month (with the lowest average wind speed) is August (4.7mph).

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Average humidity in December
Fairfax, VA

Average humidity in December - Fairfax, VA
  • Average humidity in December: 77%

The months with the highest relative humidity are October and December (77%).
The month with the lowest relative humidity is July (71%).

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Average rainfall in December
Fairfax, VA

Average rainfall in December - Fairfax, VA
  • Average rainfall in December: 2.72"

The wettest month (with the highest rainfall) is August (3.78").
The driest month (with the least rainfall) is September (2.01").

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Average rainfall days in December
Fairfax, VA

Average rainfall days in December - Fairfax, VA
  • Average rainfall days in December: 10.9 days

The months with the highest number of rainy days are May and August (17.3 days).
The month with the least rainy days is November (9.1 days).

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Average snowfall in December
Fairfax, VA

Average snowfall in December - Fairfax, VA
  • Average snowfall in December: 1.73"

The month with the highest snowfall is January (3.54").
The months with the least snowfall are May, June, July, August, September and October (0").

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Average snowfall days in December
Fairfax, VA

Average snowfall days in December - Fairfax, VA
  • Average snowfall days in December: 3.1 days

The month with the highest number of snowfall days is January (5.6 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
Fairfax, VA

Average daylight in December / Average sunshine in December - Fairfax, VA
  • Average daylight in December: 9h and 3min

The month with the longest days is June (Average daylight: 14h and 48min).
The month with the shortest days is December (Average daylight: 9h and 30min).

  • Average sunshine in December: 5h and 1min

The month with the most sunshine is July (Average sunshine: 10h and 48min).
The months with the least sunshine are January, February and December (Average sunshine: 5h and 12min).

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Average sunshine days in December
Fairfax, VA

Average sunshine days in December - Fairfax, VA
  • Average sunshine days in December: 16.9 days

The month with the most sunshine days is November (19.6 days).
The month with the least sunshine days is July (11.3 days).

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Average UV index in December
Fairfax, VA

Average UV index in December - Fairfax, VA
  • Average UV index in December: 2

The months with the highest UV index are May, June, July and August (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 December
Fairfax, VA

Average cloud cover in December - Fairfax, VA
  • Average cloud cover in December: 44

The month with the most cloud cover is March (Cloud cover 46).
The month with the least cloud cover is July (Cloud cover 30).

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Average visibility in December
Fairfax, VA

Average visibility in December - Fairfax, VA
  • Average visibility in December: 6mi

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

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Fairfax, Virginia, USA

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