December weather forecastGreencastle, PA
December
Weather in December
The first month of the winter, December, is also a wintry month in Greencastle, Pennsylvania, with an average temperature ranging between min 28.9°F (-1.7°C) and max 41.2°F (5.1°C).Temperature
A change in temperatures is noted as November gives way to December, with average highs reducing from a cool 50.5°F (10.3°C) to a wintry 41.2°F (5.1°C). Throughout December, an average low-temperature of 28.9°F (-1.7°C) is expected in Greencastle.Humidity
The months with the highest humidity are February, May, October and December, with an average relative humidity of 79%.Rainfall
In Greencastle, in December, during 10.3 rainfall days, 2.01" (51mm) of precipitation is typically accumulated. Throughout the year, there are 161.8 rainfall days, and 28.07" (713mm) of precipitation is accumulated.Snowfall
January through April, October through December are months with snowfall. In Greencastle, in December, snow falls for 4.7 days, with typically accumulated 2.13" (54mm) of snow. In Greencastle, during the entire year, snow falls for 26.6 days and aggregates up to 14.69" (373mm) of snow.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 7:13 am and sunset at 4:46 pm. On the last day of the month, sunrise is at 7:31 am and sunset at 4:56 pm EST.
Sunshine
The average sunshine in December is 4.8h.UV index
January, February, 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 minimal health vulnerability from exposure to the Sun's UV radiation for the average person.Note: In December, the maximum UV index of 2 translates into these guidelines:
While most people can stay under the sun for an hour without burning, children must always be guarded against sun exposure. Sun exposure should be minimized, especially during midday, to avoid harmful UV radiation. Sunglasses that ward off UVA and UVB rays play a pivotal role in reducing solar eye damage. Consider carefully! The reflective quality of snow can almost double the intensity of the Sun's UV radiation.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Greencastle, PA
- Average high temperature in December: 41.2°F
The warmest month (with the highest average high temperature) is July (84.4°F).
The month with the lowest average high temperature is January (35.4°F).
- Average low temperature in December: 28.9°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 (22.5°F).
Average pressure in December
Greencastle, 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
Greencastle, PA
- Average wind speed in December: 7mph
The windiest month (with the highest average wind speed) is January (7.7mph).
The calmest months (with the lowest average wind speed) are July and August (4.5mph).
Average humidity in December
Greencastle, PA
- Average humidity in December: 79%
The months with the highest relative humidity are February, May, October and December (79%).
The months with the lowest relative humidity are April and July (75%).
Average rainfall in December
Greencastle, PA
- Average rainfall in December: 2.01"
The wettest month (with the highest rainfall) is May (3.15").
The driest month (with the least rainfall) is January (1.85").
Average rainfall days in December
Greencastle, PA
- Average rainfall days in December: 10.3 days
The month with the highest number of rainy days is May (18.8 days).
The month with the least rainy days is November (9 days).
Average snowfall in December
Greencastle, PA
- Average snowfall in December: 2.13"
The month with the highest snowfall is January (4.53").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in December
Greencastle, PA
- Average snowfall days in December: 4.7 days
The month with the highest number of snowfall days is January (8.1 days).
The months with the least snowfall days are May, June, July, August and September (0 days).
Average daylight in December /
Average sunshine in December
Greencastle, PA
- Average daylight in December: 9h and 24min
The month with the longest days is June (Average daylight: 14h and 54min).
The month with the shortest days is December (Average daylight: 9h and 24min).
- Average sunshine in December: 4h and 48min
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
Greencastle, PA
- Average sunshine days in December: 17.1 days
The month with the most sunshine days is November (18.5 days).
The month with the least sunshine days is May (10.4 days).
Average UV index in December
Greencastle, 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, November and December (UV index 2).
Average cloud cover in December
Greencastle, PA
- Average cloud cover in December: 50
The months with the most cloud cover are January, February and December (Cloud cover 50).
The month with the least cloud cover is July (Cloud cover 32).
Average visibility in December
Greencastle, PA
- Average visibility in December: 5mi
The months with the highest visibility are April, June, July, August and November (6mi).
The months with the lowest visibility are January, February, March, May, September, October and December (5mi).
