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 decrease of average high-temperatures is mild in December, with a decline from a cool 50.9°F (10.5°C) in November to a wintry 41.9°F (5.5°C). Grantley's nighttime temperature in December drops to an average of 30.4°F (-0.9°C).Humidity
In Grantley, Pennsylvania, the average relative humidity in December is 79%.Rainfall
In Grantley, in December, it is raining for 8.7 days, with typically 1.61" (41mm) of accumulated precipitation. Throughout the year, there are 139.8 rainfall days, and 22.95" (583mm) of precipitation is accumulated.Snowfall
January through May, October through December are months with snowfall. In December, it is snowing for 3 days. Throughout December, 1.22" (31mm) of snow is accumulated. Throughout the year, there are 18.4 snowfall days, and 9.13" (232mm) 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 7:10 am and sunset at 4:42 pm. On the last day of the month, sunrise is at 7:28 am and sunset at 4:52 pm EST.
Sunshine
The average sunshine in December is 4.9h.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 reading of 2, and below, represents a minimal health hazard from unsafe exposure to UV radiation for the ordinary person.Note: The UV index of 2 during December leads to these advisories:
Extended time in the sun generally does not harm most, but those with sensitive skin, infants, and children should always be protected. Avoiding the Sun's peak radiation during midday hours is essential for health and safety. Equip yourself with UVA and UVB-filtering sunglasses on clear, sunny days. Be cautious! The UV radiation from the Sun can be magnified almost twofold by snow reflection.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
How cold is December?
What is the average humidity in December in Grantley?
How many days does it rain in December?
How much does it snow in December?
What is the month with the shortest days?
What is the average length of the day in December?
What time are sunrise and sunset in December?
How many hours of sunshine does Grantley have in December?
What is the month with the lowest UV index?
What is the UV index intensity in December?
Average temperature in December
Grantley, PA
- Average high temperature in December: 41.9°F
The warmest month (with the highest average high temperature) is July (83.5°F).
The month with the lowest average high temperature is January (35.8°F).
- Average low temperature in December: 30.4°F
The month with the highest average low temperature is July (65.5°F).
The coldest month (with the lowest average low temperature) is January (23.4°F).
Average pressure in December
Grantley, 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 (29.94"Hg).
Average wind speed in December
Grantley, PA
- Average wind speed in December: 8.2mph
The windiest month (with the highest average wind speed) is March (8.9mph).
The calmest month (with the lowest average wind speed) is August (5.1mph).
Average humidity in December
Grantley, PA
- Average humidity in December: 79%
The month with the highest relative humidity is May (81%).
The months with the lowest relative humidity are March, April and November (76%).
Average rainfall in December
Grantley, PA
- Average rainfall in December: 1.61"
The wettest month (with the highest rainfall) is August (2.8").
The driest month (with the least rainfall) is February (1.26").
Average rainfall days in December
Grantley, PA
- Average rainfall days in December: 8.7 days
The month with the highest number of rainy days is May (15.9 days).
The month with the least rainy days is January (6.3 days).
Average snowfall in December
Grantley, PA
- Average snowfall in December: 1.22"
The month with the highest snowfall is March (3.23").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in December
Grantley, PA
- Average snowfall days in December: 3 days
The month with the highest number of snowfall days is February (5 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in December /
Average sunshine in December
Grantley, 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 36min).
The month with the least sunshine is February (Average sunshine: 4h and 42min).
Average sunshine days in December
Grantley, PA
- Average sunshine days in December: 18.6 days
The month with the most sunshine days is January (20.4 days).
The month with the least sunshine days is May (11.7 days).
Average UV index in December
Grantley, PA
- Average UV index in December: 2
The months with the highest UV index are May, 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
Grantley, PA
- Average cloud cover in December: 47
The months with the most cloud cover are February and March (Cloud cover 48).
The month with the least cloud cover is July (Cloud cover 31).
Average visibility in December
Grantley, 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).
Grantley, Pennsylvania, USA
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