December weather forecast
Shartlesville, PA

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Weather in December

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

Temperature

In Shartlesville, the average high-temperature in December drops from a frosty 49.5°F (9.7°C) in November to a cold 40.1°F (4.5°C). Shartlesville cools down to an average low-temperature of 28.6°F (-1.9°C) throughout the month of December.

Humidity

The average relative humidity in December is 81%.

Rainfall

In Shartlesville, in December, during 10.8 rainfall days, 2.01" (51mm) of precipitation is typically accumulated. In Shartlesville, during the entire year, the rain falls for 148.7 days and collects up to 26.42" (671mm) of precipitation.

Snowfall

January through May, October through December are months with snowfall. In December, it is snowing for 4.5 days. Throughout December, 1.38" (35mm) of snow is accumulated. In Shartlesville, during the entire year, snow falls for 26.2 days and aggregates up to 13.58" (345mm) of snow.

Daylight

The month with the shortest days is December, with an average of 9h and 18min of daylight.
On the first day of December, sunrise is at 7:09 am and sunset at 4:38 pm. On the last day of the month, sunrise is at 7:27 am and sunset at 4:47 pm EST.

Sunshine

In December, the average sunshine is 4.6h.

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 of 2, and less, symbolizes a low health risk from exposure to the Sun's UV radiation for the ordinary person.
Note: The maximum UV index, 2 during December, leads to the following recommendations:
For the majority, extended sun exposure is not of great concern. Infants and people with sensitive skin must always be protected. The Sun's UV radiation is especially harmful around midday, so reduce exposure and stay safe. It's wise to wear UVA and UVB-blocking sunglasses when the sun shines brightly. Keep in mind! Snow's reflective quality can nearly double the intensity of the Sun's UV radiation.

Frequently asked questions

How cold is December?

The average high-temperature, in December, in Shartlesville, is 40.1°F (4.5°C), while the average low-temperature is 28.6°F (-1.9°C). In July, the average heat index (a.k.a. 'felt air temperature', 'feels like'), which factors the actual air temperature with the relative humidity, is computed to be 89.6°F (32°C).

What is the average humidity in December?

The average relative humidity in December is 81%.

How many days does it rain in December?

In December, the rain falls for 10.8 days. Throughout December, 2.01" (51mm) of precipitation is accumulated.

How many days does it snow in December?

In December, it is snowing for 4.5 days. Throughout December, 1.38" (35mm) of snow is accumulated.

What is the month with the shortest days?

December has the shortest days of the year, with an average of 9h and 18min of daylight.

What is the average length of the day in December?

In December, the average day length is 9h and 20min.

When are sunrise and sunset in December?

In December, on the first day of the month, sunrise is at 7:09 am and sunset at 4:38 pm. On the last day of the month, sunrise is at 7:27 am and sunset at 4:47 pm EST.

How long on average sun shines in December?

The average sunshine duration in December is 4.6h.

When is the lowest UV index?

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

What is the UV index intensity in December?

In December, the average daily maximum UV index in Shartlesville is 2. A UV Index of 2, and less, symbolizes a minimal health vulnerability from unprotected exposure to 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
Shartlesville, PA

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

The warmest month (with the highest average high temperature) is July (82.4°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 (62.6°F).
The coldest month (with the lowest average low temperature) is January (21.6°F).

Average pressure in December
Shartlesville, PA

Average pressure in December - Shartlesville, PA
  • Average pressure in December: 30.09"Hg

The month with the highest atmospheric pressure is November (30.13"Hg).
The month with the lowest atmospheric pressure is June (29.94"Hg).

Average wind speed in December
Shartlesville, PA

Average wind speed in December - Shartlesville, 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 (4.8mph).

Average humidity in December
Shartlesville, PA

Average humidity in December - Shartlesville, PA
  • Average humidity in December: 81%

The month with the highest relative humidity is February (82%).
The month with the lowest relative humidity is April (76%).

Average rainfall in December
Shartlesville, PA

Average rainfall in December - Shartlesville, PA
  • Average rainfall in December: 2.01"

The wettest month (with the highest rainfall) is August (2.87").
The driest month (with the least rainfall) is September (1.61").

Average rainfall days in December
Shartlesville, PA

Average rainfall days in December - Shartlesville, PA
  • Average rainfall days in December: 10.8 days

The month with the highest number of rainy days is May (17.1 days).
The month with the least rainy days is January (7.7 days).

Average snowfall in December
Shartlesville, PA

Average snowfall in December - Shartlesville, PA
  • Average snowfall in December: 1.38"

The month with the highest snowfall is March (3.86").
The months with the least snowfall are June, July, August and September (0").

Average snowfall days in December
Shartlesville, PA

Average snowfall days in December - Shartlesville, PA
  • Average snowfall days in December: 4.5 days

The month with the highest number of snowfall days is January (8.3 days).
The months with the least snowfall days are June, July, August and September (0 days).

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

Average daylight in December / Average sunshine in December - Shartlesville, 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 18min).

  • Average sunshine in December: 4h and 4min

The month with the most sunshine is July (Average sunshine: 10h and 24min).
The month with the least sunshine is February (Average sunshine: 4h and 24min).

Average sunshine days in December
Shartlesville, PA

Average sunshine days in December - Shartlesville, PA
  • Average sunshine days in December: 16.8 days

The month with the most sunshine days is November (18.8 days).
The month with the least sunshine days is May (10.8 days).

Average UV index in December
Shartlesville, PA

Average UV index in December - Shartlesville, PA
  • Average UV index in December: 2

The month with the highest UV index is June (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
Shartlesville, PA

Average cloud cover in December - Shartlesville, PA
  • Average cloud cover in December: 51

The month with the most cloud cover is February (Cloud cover 52).
The month with the least cloud cover is July (Cloud cover 33).

Average visibility in December
Shartlesville, PA

Average visibility in December - Shartlesville, PA
  • Average visibility in December: 5mi

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

Shartlesville, Pennsylvania, USA

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