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 commencement of December indicates a shift in the average high-temperature, receding from November's fresh 50.5°F (10.3°C) to a cold 41°F (5°C). Grantham reports a consistent average low-temperature of 29.7°F (-1.3°C) throughout December nights.Humidity
In Grantham, the average relative humidity in December is 79%.Rainfall
In Grantham, Pennsylvania, during December, the rain falls for 9.5 days and regularly aggregates up to 1.26" (32mm) of precipitation. In Grantham, Pennsylvania, during the entire year, the rain falls for 137.7 days and collects up to 18.43" (468mm) of precipitation.Snowfall
January through April, October through December are months with snowfall. In Grantham, in December, during 4.4 snowfall days, 1.14" (29mm) of snow is typically accumulated. In Grantham, during the entire year, snow falls for 23.7 days and aggregates up to 8.62" (219mm) of snow.Daylight
With an average of 9h and 24min of daylight, December has the shortest days of the year.On the first day of December, 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.
Sunshine
In Grantham, the average sunshine in December is 4.8h.UV index
January through March, November and December, with an average maximum UV index of 2, are months with the lowest UV index in Grantham. A UV Index estimate of 2, and below, represents a low threat to health from unprotected exposure to Sun's UV rays for ordinary individuals.Note: A maximum UV index of 2 in December translates into the following recommendations:
Prolonged sun exposure should always be prevented in babies, children, and those with sensitive skin. To guard against the harmful effects of the Sun, minimize exposure during midday. A wide-brim hat offers excellent sun protection for the eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Guard yourself! Snow reflection can almost double the UV radiation from the Sun.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
How cold is it in December?
What is the average humidity in December?
How many days does it rain in December?
How many days does it snow in December?
What is the month with the shortest days?
How many hours of daylight does Grantham have in December?
When is the sunrise / sunset in December?
How long on average sun shines in December?
What is the month with the lowest UV index?
How high is the UV index in December?
Average temperature in December
Grantham, PA
- Average high temperature in December: 41°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 (35.2°F).
- Average low temperature in December: 29.7°F
The month with the highest average low temperature is July (64.6°F).
The coldest month (with the lowest average low temperature) is January (22.5°F).
Average pressure in December
Grantham, 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
Grantham, PA
- Average wind speed in December: 7.8mph
The windiest months (with the highest average wind speed) are February, March and April (8.4mph).
The calmest months (with the lowest average wind speed) are July and August (5mph).
Average humidity in December
Grantham, PA
- Average humidity in December: 79%
The months with the highest relative humidity are February and May (80%).
The month with the lowest relative humidity is April (75%).
Average rainfall in December
Grantham, PA
- Average rainfall in December: 1.26"
The wettest months (with the highest rainfall) are May and July (2.05").
The driest month (with the least rainfall) is January (1.14").
Average rainfall days in December
Grantham, PA
- Average rainfall days in December: 9.5 days
The month with the highest number of rainy days is May (15.6 days).
The month with the least rainy days is January (6.3 days).
Average snowfall in December
Grantham, PA
- Average snowfall in December: 1.14"
The month with the highest snowfall is January (2.52").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in December
Grantham, PA
- Average snowfall days in December: 4.4 days
The month with the highest number of snowfall days is January (7.2 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in December /
Average sunshine in December
Grantham, 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 36min).
Average sunshine days in December
Grantham, PA
- Average sunshine days in December: 18.1 days
The month with the most sunshine days is November (20 days).
The month with the least sunshine days is May (12.2 days).
Average UV index in December
Grantham, 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
Grantham, PA
- Average cloud cover in December: 49
The months with the most cloud cover are February and December (Cloud cover 49).
The month with the least cloud cover is July (Cloud cover 30).
Average visibility in December
Grantham, 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).
Grantham, Pennsylvania, USA
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