December weather forecast
Mechanicsburg, PA

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Weather in December

The first month of the winter, December, is also an icy month in Mechanicsburg, Pennsylvania, with an average temperature fluctuating between 41°F (5°C) and 29.7°F (-1.3°C).

Temperature

With December's arrival, Mechanicsburg sees a decrease in average high-temperatures, moving from a cool 50°F (10°C) in November to a wintry 41°F (5°C). During December, the average low-temperature is a subzero cold 29.7°F (-1.3°C).

Humidity

The average relative humidity in December is 79%.

Rainfall

In December, the rain falls for 8.4 days. Throughout December, 0.87" (22mm) of precipitation is accumulated. In Mechanicsburg, during the entire year, the rain falls for 122.3 days and collects up to 11.73" (298mm) of precipitation.

Snowfall

January through April, November and December are months with snowfall. In Mechanicsburg, in December, snow falls for 3.5 days, with typically accumulated 0.59" (15mm) of snow. Throughout the year, there are 19.9 snowfall days, and 4.29" (109mm) of snow is accumulated.

Daylight

December has the shortest days of the year in Mechanicsburg, with an average of 9h and 24min of daylight.
On the first day of the month, sunrise is at 7:11 am and sunset at 4:42 pm. On the last day of December, sunrise is at 7:30 am and sunset at 4:52 pm EST.

Sunshine

The average sunshine in December is 4.7h.

UV index

January through March, November and December, with an average maximum UV index of 2, are months with the lowest UV index in Mechanicsburg. A UV Index of 2, and less, symbolizes a low threat to health from unsafe exposure to UV radiation for the ordinary person.
Note: During December, 2 as the daily maximum UV index converts into the following advice:
While most people are not greatly affected by extended sun exposure, those with fair skin, babies, and children must always have protection. Sun exposure should be minimized, especially during midday, to avoid harmful UV radiation. Your best bet for sun defense on the face, eyes, and neck is a hat with a wide brim. Take to heart! Snow reflection can almost magnify the Sun's UV radiation twofold.
Updated: Jun 10, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

How cold is December?

During December, Mechanicsburg experiences an average high-temperature of 41°F (5°C) and a low-temperature of 29.7°F (-1.3°C). In August, the average heat index (a.k.a. 'feels like', 'apparent temperature'), which takes the relative humidity and factors it into the air temperature reading, is appraised at 87.8°F (31°C).

What is the average humidity in December?

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

How many days does it rain in December?

In Mechanicsburg, during December, the rain falls for 8.4 days and regularly aggregates up to 0.87" (22mm) of precipitation.

How many days does it snow in December?

In Mechanicsburg, during December, snow falls for 3.5 days and regularly aggregates up to 0.59" (15mm) of snow.

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?

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

When is the sunrise / sunset in December?

In December, on the first day of the month, sunrise is at 7:11 am and sunset at 4:42 pm. On the last day of the month, sunrise is at 7:30 am and sunset at 4:52 pm EST.

How many hours of sunshine does Mechanicsburg have in December?

In December, the average sunshine duration is 4.7h.

When is 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 reading in December?

In December, the average daily maximum UV index is 2. A UV Index of 2, and less, symbolizes a minimal hazard to health from exposure to Sun's UV rays.
Average high temperature
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
Mechanicsburg, PA

Average temperature in December - Mechanicsburg, PA
  • Average high temperature in December: 41°F

The warmest month (with the highest average high temperature) is July (83.8°F).
The month with the lowest average high temperature is January (35.1°F).

  • Average low temperature in December: 29.7°F

The month with the highest average low temperature is July (63.5°F).
The coldest month (with the lowest average low temperature) is January (22.1°F).

Average pressure in December
Mechanicsburg, PA

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

The month with the highest atmospheric pressure is November (30.13"Hg).
The month with the lowest atmospheric pressure is June (29.95"Hg).

Average wind speed in December
Mechanicsburg, PA

Average wind speed in December - Mechanicsburg, PA
  • Average wind speed in December: 7.6mph

The windiest month (with the highest average wind speed) is March (8.2mph).
The calmest months (with the lowest average wind speed) are July and August (4.8mph).

Average humidity in December
Mechanicsburg, PA

Average humidity in December - Mechanicsburg, PA
  • Average humidity in December: 79%

The month with the highest relative humidity is February (80%).
The months with the lowest relative humidity are March and April (75%).

Average rainfall in December
Mechanicsburg, PA

Average rainfall in December - Mechanicsburg, PA
  • Average rainfall in December: 0.87"

The wettest month (with the highest rainfall) is August (1.3").
The driest months (with the least rainfall) are January and February (0.71").

Average rainfall days in December
Mechanicsburg, PA

Average rainfall days in December - Mechanicsburg, PA
  • Average rainfall days in December: 8.4 days

The month with the highest number of rainy days is May (13.9 days).
The month with the least rainy days is January (5.7 days).

Average snowfall in December
Mechanicsburg, PA

Average snowfall in December - Mechanicsburg, PA
  • Average snowfall in December: 0.59"

The month with the highest snowfall is February (1.3").
The months with the least snowfall are May, June, July, August, September and October (0").

Average snowfall days in December
Mechanicsburg, PA

Average snowfall days in December - Mechanicsburg, PA
  • Average snowfall days in December: 3.5 days

The month with the highest number of snowfall days is January (6.3 days).
The months with the least snowfall days are June, July, August, September and October (0 days).

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

Average daylight in December / Average sunshine in December - Mechanicsburg, 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 4min

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 30min).

Average sunshine days in December
Mechanicsburg, PA

Average sunshine days in December - Mechanicsburg, PA
  • Average sunshine days in December: 20.2 days

The month with the most sunshine days is November (21.8 days).
The month with the least sunshine days is July (14.1 days).

Average UV index in December
Mechanicsburg, PA

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

The months with the highest UV index are May, June and July (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
Mechanicsburg, PA

Average cloud cover in December - Mechanicsburg, PA
  • Average cloud cover in December: 50

The months with the most cloud cover are February and December (Cloud cover 50).
The month with the least cloud cover is July (Cloud cover 31).

Average visibility in December
Mechanicsburg, PA

Average visibility in December - Mechanicsburg, 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).

Mechanicsburg, Pennsylvania, USA

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