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
Mount Gretna in December demonstrates a small temperature transition, adjusting from an average high of a frosty 49.5°F (9.7°C) in November to a wintry 40.3°F (4.6°C). An average minimum temperature of 29.3°F (-1.5°C) marks the month of December.Humidity
The average relative humidity in December is 80%.Rainfall
In December, in Mount Gretna, the rain falls for 9.2 days. Throughout December, 1.1" (28mm) of precipitation is accumulated. In Mount Gretna, during the entire year, the rain falls for 137.4 days and collects up to 16.26" (413mm) of precipitation.Snowfall
Months with snowfall in Mount Gretna are January through May, October through December. In Mount Gretna, Pennsylvania, in December, during 3.3 snowfall days, 0.98" (25mm) of snow is typically accumulated. Throughout the year, in Mount Gretna, there are 19.5 snowfall days, and 6.69" (170mm) of snow is accumulated.Daylight
December has the shortest days of the year in Mount Gretna, with an average of 9h and 24min of daylight.On the first day of December, sunrise is at 7:09 am and sunset at 4:40 pm. On the last day of the month, sunrise is at 7:28 am and sunset at 4:50 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 in Mount Gretna. A UV Index reading of 2, and below, represents a low threat to health from unprotected exposure to Sun's UV rays for ordinary individuals.Note: In December, the maximum UV index of 2 translates into these guidelines:
Despite most people tolerating extended sun exposure, it is critical to always protect those with sensitive skin, infants, and children. It's recommended to limit sun exposure when its radiation is at its peak during midday. Equip yourself with UVA and UVB-filtering sunglasses on clear, sunny days. Note this! The Sun's UV radiation can nearly be doubled by the reflection off snow.
Frequently asked questions
Is it cold in Mount Gretna during December?
What is the average humidity in December in Mount Gretna?
How much does it rain in Mount Gretna in December?
How many days does it snow in December in Mount Gretna?
What is the month with the shortest days in Mount Gretna?
What is the average length of the day in December in Mount Gretna?
When are sunrise and sunset in December in Mount Gretna?
How many hours of sunshine does Mount Gretna have in December?
What are the months with the lowest UV index in Mount Gretna?
What is the UV index intensity in December in Mount Gretna?
Average temperature in December
Mount Gretna, PA
- Average high temperature in December: 40.3°F
The warmest month (with the highest average high temperature) is July (82°F).
The month with the lowest average high temperature is January (33.8°F).
- Average low temperature in December: 29.3°F
The month with the highest average low temperature is July (63.1°F).
The coldest month (with the lowest average low temperature) is January (21.6°F).
Average pressure in December
Mount Gretna, 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 (29.94"Hg).
Average wind speed in December
Mount Gretna, PA
- Average wind speed in December: 8mph
The windiest month (with the highest average wind speed) is March (8.8mph).
The calmest month (with the lowest average wind speed) is August (4.8mph).
Average humidity in December
Mount Gretna, PA
- Average humidity in December: 80%
The months with the highest relative humidity are February, May and October (81%).
The month with the lowest relative humidity is April (76%).
Average rainfall in December
Mount Gretna, PA
- Average rainfall in December: 1.1"
The wettest month (with the highest rainfall) is August (2.13").
The driest month (with the least rainfall) is February (0.94").
Average rainfall days in December
Mount Gretna, PA
- Average rainfall days in December: 9.2 days
The month with the highest number of rainy days is May (15.9 days).
The month with the least rainy days is January (6.7 days).
Average snowfall in December
Mount Gretna, PA
- Average snowfall in December: 0.98"
The month with the highest snowfall is January (1.97").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in December
Mount Gretna, PA
- Average snowfall days in December: 3.3 days
The month with the highest number of snowfall days is January (5.2 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in December /
Average sunshine in December
Mount Gretna, 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 24min).
The month with the least sunshine is February (Average sunshine: 4h and 30min).
Average sunshine days in December
Mount Gretna, PA
- Average sunshine days in December: 18.7 days
The month with the most sunshine days is January (20.3 days).
The month with the least sunshine days is May (11.5 days).
Average UV index in December
Mount Gretna, 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
Mount Gretna, PA
- Average cloud cover in December: 51
The months with the most cloud cover are February and December (Cloud cover 51).
The month with the least cloud cover is July (Cloud cover 32).
Average visibility in December
Mount Gretna, PA
- Average visibility in December: 6mi
The months with the highest visibility are January, February, March, April, June, July, November and December (6mi).
The months with the lowest visibility are May, August, September and October (5mi).
Mount Gretna, Pennsylvania, USA
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