Contents
- Weather in December
- Frequently asked questions
- Average temperature in December
- Average pressure in December
- Average wind speed in December
- Average humidity in December
- Average rainfall in December
- Average rainfall days in December
- Average snowfall in December
- Average snowfall days in December
- Average daylight in December
- Average sunshine in December
- Average sunshine days in December
- Average UV index in December
- Average cloud cover in December
- Average visibility in December
Weather in December
Temperature
The onset of December brings a small shift in high-temperatures, falling from a cool 50.4°F (10.2°C) in November to an icy 41.5°F (5.3°C). South Mountain, in the month of December, anticipates a consistent average low-temperature of 29.3°F (-1.5°C).Humidity
In December, the average relative humidity is 79%.Rainfall
In South Mountain, Pennsylvania, during December, the rain falls for 7.7 days and regularly aggregates up to 0.71" (18mm) of precipitation. In South Mountain, during the entire year, the rain falls for 125.3 days and collects up to 10.59" (269mm) of precipitation.Snowfall
Months with snowfall are January through April, November and December. In South Mountain, during December, snow falls for 2.9 days and regularly aggregates up to 0.43" (11mm) of snow. Throughout the year, in South Mountain, Pennsylvania, there are 20.2 snowfall days, and 3.54" (90mm) of snow is accumulated.Daylight
December has the shortest days of the year, with an average of 9h and 24min of daylight.On the first day of December, sunrise is at 7:12 am and sunset at 4:45 pm. On the last day of the month, sunrise is at 7:31 am and sunset at 4:55 pm EST.
Sunshine
In South Mountain, Pennsylvania, the average sunshine in December is 4.8h.UV index
The months with the lowest UV index are January, February, November and December, with an average maximum UV index of 2. A UV Index value of 2, and less, symbolizes a low threat to health from unprotected exposure to Sun's UV rays for the ordinary person.Note: The maximum daily UV index of 2 during December translates into the following directions:
Unlike children, who always need sun protection, most individuals can remain in the sun for up to an hour without getting burnt. Avoiding direct sunlight during midday hours helps reduce the risk from intense UV radiation. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes. Note this! The Sun's UV radiation can nearly be doubled by the reflection off snow.
Frequently asked questions
Is it cold in South Mountain during December?
What is the average humidity in December in South Mountain?
How many days does it rain in December in South Mountain?
How much does it snow in South Mountain in December?
What is the month with the shortest days in South Mountain?
What is the average length of the day in December in South Mountain?
When are sunrise and sunset in December in South Mountain?
How long on average sun shines in December in South Mountain?
What is the month with the lowest UV index in South Mountain?
What is the UV index intensity in December in South Mountain?
Average temperature in December
South Mountain, PA
- Average high temperature in December: 41.5°F
The warmest month (with the highest average high temperature) is July (84.2°F).
The month with the lowest average high temperature is January (35.4°F).
- Average low temperature in December: 29.3°F
The month with the highest average low temperature is July (63.7°F).
The coldest month (with the lowest average low temperature) is January (22.6°F).
Average pressure in December
South Mountain, 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).
Average wind speed in December
South Mountain, PA
- Average wind speed in December: 7.3mph
The windiest month (with the highest average wind speed) is January (8mph).
The calmest months (with the lowest average wind speed) are July and August (4.7mph).
Average humidity in December
South Mountain, PA
- Average humidity in December: 79%
The months with the highest relative humidity are February, May and October (80%).
The month with the lowest relative humidity is July (75%).
Average rainfall in December
South Mountain, PA
- Average rainfall in December: 0.71"
The wettest month (with the highest rainfall) is May (1.26").
The driest month (with the least rainfall) is September (0.55").
Average rainfall days in December
South Mountain, PA
- Average rainfall days in December: 7.7 days
The month with the highest number of rainy days is May (14.9 days).
The month with the least rainy days is January (5.4 days).
Average snowfall in December
South Mountain, PA
- Average snowfall in December: 0.43"
The month with the highest snowfall is January (1.06").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in December
South Mountain, PA
- Average snowfall days in December: 2.9 days
The month with the highest number of snowfall days is January (6.7 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average daylight in December /
Average sunshine in December
South Mountain, 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 30min).
Average sunshine days in December
South Mountain, PA
- Average sunshine days in December: 20.7 days
The month with the most sunshine days is November (21.7 days).
The month with the least sunshine days is May (12.9 days).
Average UV index in December
South Mountain, PA
- Average UV index in December: 2
The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in December
South Mountain, PA
- Average cloud cover in December: 49
The months with the most cloud cover are January and February (Cloud cover 50).
The month with the least cloud cover is July (Cloud cover 32).
Average visibility in December
South Mountain, PA
- Average visibility in December: 6mi
The months with the highest visibility are March, April, June, July, November and December (6mi).
The months with the lowest visibility are January, February, May, August, September and October (5mi).
South Mountain, Pennsylvania, USA
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