December weather forecast
Washington, PA

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Weather in December

December announces the return of winter in Washington, with average temperatures dropping to a wintery 40.1°F (4.5°C). Amid the festive cheer, the weather gets frostier, with the reappearance of substantial snowfall at 0.83" (21mm). The city, blanketed by white fluff, takes on a winter wonderland persona with lights twinkling against the snow-clad background. The shorter days and longer nights become noticeable, complemented by the wintry cold and early sunsets. As the final month of the year and the onset of winter, December brings the climatic cycles full circle, rounding off Washington's weather story with a snowy flourish.

Temperature

Washington's average high-temperature decreases in December, falling from a frosty 49.5°F (9.7°C) in November to a cold 40.1°F (4.5°C). Washington's temperature drops to an average low of 28.6°F (-1.9°C) during the nights of December.

Humidity

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

Rainfall

In Washington, in December, during 9.4 rainfall days, 1.06" (27mm) of precipitation is typically accumulated. In Washington, during the entire year, the rain falls for 143 days and collects up to 14.8" (376mm) of precipitation.

Snowfall

January through May, October through December are months with snowfall. In Washington, in December, snow falls for 6.5 days, with typically accumulated 0.83" (21mm) of snow. Throughout the year, in Washington, there are 33.5 snowfall days, and 4.88" (124mm) of snow is accumulated.

Daylight

With an average of 9h and 24min of daylight, December has the shortest days of the year.
On the first day of the month, sunrise is at 7:24 am and sunset at 4:55 pm. On the last day of December, sunrise is at 7:43 am and sunset at 5:05 pm EST.

Sunshine

In Washington, Pennsylvania, the average sunshine in December is 3.5h.

UV index

December is the month with the lowest UV index, with an average maximum UV index of 1. A UV Index of 2, and less, symbolizes a low health risk from exposure to the Sun's UV radiation for ordinary individuals.
Note: The UV index of 1 during December leads to these advisories:
Infants, children, and people with sensitive skin should always have protection against lengthy periods of sun exposure. Solar radiation is at its peak intensity during midday, so it's advisable to stay indoors or in the shade. A hat with a generous brim can prevent nearly 50% of UV rays from reaching your eyes. Be aware! The intensity of the Sun's UV radiation can be amplified nearly twice due to snow reflection.
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Frequently asked questions

How cold does it get in Washington in December?

In Washington, in December, the average high-temperature is 40.1°F (4.5°C), and the average low-temperature is 28.6°F (-1.9°C). In August, the average heat index (a.k.a. 'feels like', 'real feel'), which represents the influence of relative humidity on air temperature, is calculated to be 87.8°F (31°C).

What is the average humidity in December in Washington?

In December, the average relative humidity is 84%.

How many days does it rain in December in Washington?

In Washington, Pennsylvania, 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?

With an average of 9h and 24min of daylight, December has the shortest days of the year in Washington.

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

In December, the average day length in Washington is 9h and 22min.

When are sunrise and sunset in December in Washington?

On the first day of December, sunrise is at 7:24 am and sunset at 4:55 pm. On the last day of the month, sunrise is at 7:43 am and sunset at 5:05 pm EST.

How many hours of sunshine does Washington have in December?

In December, the average sunshine duration in Washington, Pennsylvania, is 3.5h.

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

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

What is the UV index intensity in December in Washington?

In Washington, the average daily maximum UV index in December is 1. A UV Index value of 2, and less, symbolizes a minimal health vulnerability from unprotected exposure to UV radiation.
Today
Tomorrow
Long-term
YearJFMAMJJASONDecember
Nov
December
Jan
Average high temperature
49.5°F 9.7°C
40.1°F 4.5°C
33.6°F 0.9°C
Average low temperature
33.8°F 1°C
28.6°F -1.9°C
20.8°F -6.2°C
Average pressure
30.14" 766mmHg
30.11" 765mmHg
30.12" 765mmHg
Average wind speed
6.6mph 10.6km/h
7.1mph 11.4km/h
7.8mph 12.6km/h
Average max. wind speed
7.1mph 11.4km/h
7.7mph 12.4km/h
8.4mph 13.5km/h
Average wind speed gusts
10.7mph 17.2km/h
11.2mph 18km/h
12.1mph 19.5km/h
Average humidity
78%
84%
84%
Average rainfall
0.94" 24mm
1.06" 27mm
0.94" 24mm
Average rainfall days
8.1
9.4
7.5
Average snowfall
0.59" 15mm
0.83" 21mm
1.06" 27mm
Average snowfall days
2.5
6.5
9.8
Average daylight
10h 0min
9h 2min
9h 4min
Average sunshine
5h 0min
3h 3min
3h 0min
Average sunshine days
19.1
17.5
17.1
Average UV index
2
1
2
Average cloud cover
47%
64%
68%
Average visibility
6mi 9.7km
5mi 8km
5mi 8km

Average temperature in December
Washington, PA

Average temperature in December - Washington, PA
  • Average high temperature in December: 40.1°F

The warmest month (with the highest average high temperature) is July (83.3°F).
The month with the lowest average high temperature is January (33.6°F).

  • Average low temperature in December: 28.6°F

The month with the highest average low temperature is July (61.9°F).
The coldest month (with the lowest average low temperature) is January (20.8°F).

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Average pressure in December
Washington, PA

Average pressure in December - Washington, PA
  • 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
Washington, PA

Average wind speed in December - Washington, PA
  • Average wind speed in December: 7.1mph

The windiest month (with the highest average wind speed) is January (7.8mph).
The calmest month (with the lowest average wind speed) is August (4.5mph).

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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: 1.06"

The wettest month (with the highest rainfall) is July (1.65").
The driest months (with the least rainfall) are January and November (0.94").

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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: 0.83"

The month with the highest snowfall is February (1.26").
The months with the least snowfall are June, July, August and September (0").

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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: 9h and 2min

The month with the longest days is June (Average daylight: 15h and 0min).
The month with the shortest days is December (Average daylight: 9h and 24min).

  • Average sunshine in December: 3h and 3min

The month with the most sunshine is August (Average sunshine: 10h and 12min).
The month with the least sunshine is January (Average sunshine: 3h and 0min).

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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: 5mi

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

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Washington, Pennsylvania, USA

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