December weather forecast
Washington, PA

Weather in December

The first month of the winter, December, is also a wintry month in Washington, Pennsylvania, with average temperature varying between 40.1°F (4.5°C) and 28.6°F (-1.9°C).

Temperature

In December, the average high-temperature decreases, from a chilly 49.5°F (9.7°C) in November, to a wintry 40.1°F (4.5°C). The average low-temperature, in Washington, is 28.6°F (-1.9°C).

Humidity

In Washington, the average relative humidity is 84%.

Rainfall

In Washington, in December, it is raining for 9.4 days, with typically 1.06" (27mm) of accumulated precipitation. Throughout the year, in Washington, there are 143 rainfall days, and 14.8" (376mm) of precipitation is accumulated.

Snowfall

Months with snowfall are January through May, October through December. In December, it is snowing for 6.5 days. Throughout December, 0.83" (21mm) of snow is accumulated. In Washington, during the entire year, snow falls for 33.5 days, and aggregates up to 4.88" (124mm) of snow.

Daylight

With an average of 9.4h of daylight, December has the shortest days of the year.

Sunshine

The average sunshine in December is 3.5h.

UV index

December is the month with the lowest UV index in Washington, with an average maximum UV index of 1. A UV Index of 2, and less, symbolizes a minimal health vulnerability from the exposure to the Sun's UV rays for ordinary individuals.
Note: In December, the average maximum UV index of 1 translate into the following recommendations:
People with sensitive skin, children, and babies should always be protected from prolonged sun exposure. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. A wide-brim hat offers excellent sun protection for eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Tightly woven, loose-fitting clothes provide additional protection from the Sun. 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 average humidity in December in Washington?

The average relative humidity in December in Washington is 84%.

How many days does it rain in December in Washington?

In Washington, in December, during 9.4 rainfall days, 1.06" (27mm) of precipitation is typically accumulated.

How many days does it snow in December in Washington?

In December, in Washington, it is snowing for 6.5 days. Throughout December, 0.83" (21mm) of snow is accumulated.

What is the month with the shortest days in Washington?

December has the shortest days of the year in Washington, with an average of 9.4h of daylight.

How many hours of daylight does Washington have in December?

In December, the average length of the day in Washington is 9.4h.

How long on average sun shines in December in Washington?

In December, the average sunshine is 3.5h.

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

The month with the lowest UV index is December, with an average maximum UV index of 1.

What is the UV index intensity in December in Washington?

In December, the average daily maximum UV index in Washington is 1. A UV Index value of 2, and less, symbolizes a minimal hazard to health from the exposure to the Sun's UV rays.

Average temperature in December
Washington, PA

Average temperature in December - Washington, PA
  • Average high temperature in December: 4.5°C

The warmest month (with the highest average high temperature) is July (28.5°C).
The month with the lowest average high temperature is January (0.9°C).

  • Average low temperature in December: -1.9°C

The month with the highest average low temperature is July (16.6°C).
The coldest month (with the lowest average low temperature) is January (-6.2°C).

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Average pressure in December
Washington, PA

Average pressure in December - Washington, PA
  • Average pressure in December: 1019.7mbar

The month with the highest atmospheric pressure is November (1020.5mbar).
The month with the lowest atmospheric pressure is June (1014.2mbar).

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Average wind speed in December
Washington, PA

Average wind speed in December - Washington, PA
  • Average wind speed in December: 11.4km/h

The windiest month (with the highest average wind speed) is January (12.5km/h).
The calmest month (with the lowest average wind speed) is August (7.3km/h).

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Average humidity in December
Washington, PA

Average humidity in December - Washington, PA
  • Average humidity in December: 84%

The month with the highest relative humidity is February (85%).
The months with the lowest relative humidity are April, July and August (77%).

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Average rainfall in December
Washington, PA

Average rainfall in December - Washington, PA
  • Average rainfall in December: 27mm

The wettest month (with the highest rainfall) is July (42mm).
The driest months (with the least rainfall) are January and November (24mm).

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Average rainfall days in December
Washington, PA

Average rainfall days in December - Washington, PA
  • Average rainfall days in December: 9.4 days

The month with the highest number of rainy days is May (17.2 days).
The month with the least rainy days is February (7.3 days).

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Average snowfall in December
Washington, PA

Average snowfall in December - Washington, PA
  • Average snowfall in December: 21mm

The month with the highest snowfall is February (32mm).
The months with the least snowfall are June, July, August and September (0mm).

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Average snowfall days in December
Washington, PA

Average snowfall days in December - Washington, PA
  • Average snowfall days in December: 6.5 days

The month with the highest number of snowfall days is January (9.8 days).
The months with the least snowfall days are June, July, August and September (0 days).

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Average daylight in December /
Average sunshine in December
Washington, PA

Average daylight in December / Average sunshine in December - Washington, PA
  • Average daylight in December: 9.4h

The month with the longest days is June (Average daylight: 15h).
The month with the shortest days is December (Average daylight: 9.4h).

  • Average sunshine in December: 3.5h

The month with the most sunshine is August (Average sunshine: 10.2h).
The month with the least sunshine is January (Average sunshine: 3h).

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Average sunshine days in December
Washington, PA

Average sunshine days in December - Washington, PA
  • Average sunshine days in December: 17.5 days

The month with the most sunshine days is November (19.1 days).
The month with the least sunshine days is May (11.8 days).

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Average UV index in December
Washington, PA

Average UV index in December - Washington, PA
  • Average UV index in December: 1

The months with the highest UV index are June, July and August (UV index 6).
The month with the lowest UV index is December (UV index 1).

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Average cloud cover in December
Washington, PA

Average cloud cover in December - Washington, PA
  • Average cloud cover in December: 64

The month with the most cloud cover is January (Cloud cover 68).
The month with the least cloud cover is August (Cloud cover 33).

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Average visibility in December
Washington, PA

Average visibility in December - Washington, PA
  • Average visibility in December: 8km

The months with the highest visibility are April and November (9km).
The months with the lowest visibility are January, February, March, May, June, July, August, September, October and December (8km).

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