December weather forecast
Valley Forge, PA

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Weather in December

December, the first month of the winter in Valley Forge, is also a wintry month, with an average temperature fluctuating between 30.9°F (-0.6°C) and 42.3°F (5.7°C).

Temperature

The commencement of December includes a gentle temperature shift, with the average high-temperature dropping a bit from a cool 51.1°F (10.6°C) in November to an icy 42.3°F (5.7°C). During December, Valley Forge witnesses a consistent average low-temperature of 30.9°F (-0.6°C).

Humidity

In December, the average relative humidity is 79%.

Rainfall

In Valley Forge, Pennsylvania, in December, it is raining for 7.9 days, with typically 0.98" (25mm) of accumulated precipitation. In Valley Forge, during the entire year, the rain falls for 132.3 days and collects up to 13.98" (355mm) of precipitation.

Snowfall

January through March, November and December are months with snowfall. In December, it is snowing for 2.5 days. Throughout December, 0.51" (13mm) of snow is accumulated. Throughout the year, there are 15.1 snowfall days, and 2.2" (56mm) of snow is accumulated.

Daylight

The month with the shortest days is December, with an average of 9h and 24min of daylight.
On the first day of the month, sunrise is at 7:05 am and sunset at 4:36 pm. On the last day of December, sunrise is at 7:23 am and sunset at 4:46 pm EST.

Sunshine

In December, the average sunshine in Valley Forge is 4.8h.

UV index

January through March, 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 radiation for the average person.
Note: In December, an average UV index of 2 transforms into the following instructions:
For the majority, extended sun exposure is not of great concern. Infants and people with sensitive skin must always be protected. Sun exposure should be minimized, especially during midday, to avoid harmful UV radiation. To best shield against UV radiation, choose sun-safe garments and dependable sunglasses. Keep in mind! Snow's reflective quality can nearly double the intensity of the Sun's UV radiation.

Frequently asked questions

How cold does it get in December?

The high-temperature, in December, in Valley Forge, is 42.3°F (5.7°C), while the low-temperature averages to 30.9°F (-0.6°C). In August, the average heat index (a.k.a. 'feels like', 'felt air temperature'), which represents the influence of relative humidity on air temperature, is computed to be 89.6°F (32°C).

What is the average humidity in December?

In Valley Forge, the average relative humidity in December is 79%.

How many days does it rain in December?

In Valley Forge, in December, during 7.9 rainfall days, 0.98" (25mm) of precipitation is typically accumulated.

How many days does it snow in December?

In Valley Forge, in December, during 2.5 snowfall days, 0.51" (13mm) of snow is typically accumulated.

What is the month with the shortest days?

The month with the shortest days is December, with an average of 9h and 24min of daylight.

What is the average length of the day in December?

The average day length in December is 9h and 23min.

When are sunrise and sunset in December?

In December, on the first day of the month, sunrise is at 7:05 am and sunset at 4:36 pm. On the last day of the month, sunrise is at 7:23 am and sunset at 4:46 pm EST.

How many hours of sunshine does Valley Forge have in December?

In Valley Forge, the average sunshine duration in December is 4.8h.

What are the months with the lowest UV index?

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

What is the UV index intensity in December?

In Valley Forge, the average daily maximum UV index in December is 2. A UV Index estimate of 2, and below, represents a minimal hazard to health from exposure to the Sun's UV radiation.
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
Valley Forge, PA

Average temperature in December - Valley Forge, PA
  • Average high temperature in December: 42.3°F

The warmest month (with the highest average high temperature) is July (85.1°F).
The month with the lowest average high temperature is January (36°F).

  • Average low temperature in December: 30.9°F

The month with the highest average low temperature is July (66.7°F).
The coldest month (with the lowest average low temperature) is January (23.9°F).

Average pressure in December
Valley Forge, PA

Average pressure in December - Valley Forge, PA
  • Average pressure in December: 30.1"Hg

The month with the highest atmospheric pressure is November (30.12"Hg).
The month with the lowest atmospheric pressure is June (29.94"Hg).

Average wind speed in December
Valley Forge, PA

Average wind speed in December - Valley Forge, PA
  • Average wind speed in December: 7.7mph

The windiest month (with the highest average wind speed) is March (8.3mph).
The calmest month (with the lowest average wind speed) is August (5.2mph).

Average humidity in December
Valley Forge, PA

Average humidity in December - Valley Forge, PA
  • Average humidity in December: 79%

The month with the highest relative humidity is February (80%).
The months with the lowest relative humidity are April and July (74%).

Average rainfall in December
Valley Forge, PA

Average rainfall in December - Valley Forge, PA
  • Average rainfall in December: 0.98"

The wettest month (with the highest rainfall) is August (1.77").
The driest month (with the least rainfall) is February (0.75").

Average rainfall days in December
Valley Forge, PA

Average rainfall days in December - Valley Forge, PA
  • Average rainfall days in December: 7.9 days

The month with the highest number of rainy days is May (15.3 days).
The month with the least rainy days is January (6.9 days).

Average snowfall in December
Valley Forge, PA

Average snowfall in December - Valley Forge, PA
  • Average snowfall in December: 0.51"

The months with the highest snowfall are January and February (0.59").
The months with the least snowfall are April, May, June, July, August, September and October (0").

Average snowfall days in December
Valley Forge, PA

Average snowfall days in December - Valley Forge, PA
  • Average snowfall days in December: 2.5 days

The month with the highest number of snowfall days is February (4.9 days).
The months with the least snowfall days are April, May, June, July, August, September and October (0 days).

Average daylight in December /
Average sunshine in December
Valley Forge, PA

Average daylight in December / Average sunshine in December - Valley Forge, 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: 4h and 5min

The month with the most sunshine is July (Average sunshine: 10h and 30min).
The month with the least sunshine is February (Average sunshine: 4h and 36min).

Average sunshine days in December
Valley Forge, PA

Average sunshine days in December - Valley Forge, PA
  • Average sunshine days in December: 20.4 days

The month with the most sunshine days is January (20.7 days).
The month with the least sunshine days is June (12.8 days).

Average UV index in December
Valley Forge, PA

Average UV index in December - Valley Forge, PA
  • 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, March, November and December (UV index 2).

Average cloud cover in December
Valley Forge, PA

Average cloud cover in December - Valley Forge, PA
  • Average cloud cover in December: 48

The month with the most cloud cover is February (Cloud cover 49).
The month with the least cloud cover is July (Cloud cover 32).

Average visibility in December
Valley Forge, PA

Average visibility in December - Valley Forge, PA
  • Average visibility in December: 6mi

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

Valley Forge, Pennsylvania, USA

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