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
December's onset brings a slight change in high-temperatures, falling from a chilly 46.9°F (8.3°C) in November to a cold 37°F (2.8°C). December's average low-temperature reading settles at a subzero cold 26.2°F (-3.2°C).Humidity
In December, the average relative humidity is 87%.Rainfall
In Mercer, during December, the rain falls for 11.3 days and regularly aggregates up to 2.8" (71mm) of precipitation. In Mercer, during the entire year, the rain falls for 180.8 days and collects up to 36.65" (931mm) of precipitation.Snowfall
Months with snowfall are January through May, October through December. In Mercer, in December, snow falls for 14.9 days, with typically accumulated 6.18" (157mm) of snow. Throughout the year, there are 76.2 snowfall days, and 32.36" (822mm) of snow is accumulated.Daylight
December has the shortest days of the year, with an average of 9h and 18min of daylight.On the first day of the month, sunrise is at 7:27 am and sunset at 4:52 pm. On the last day of December, in Mercer, sunrise is at 7:46 am and sunset at 5:02 pm EST.
Sunshine
The average sunshine in December is 2.8h.UV index
With an average maximum UV index of 1, December is the month with the lowest UV index in Mercer. A UV Index estimate of 2, and below, represents a low threat to health from unsafe exposure to UV radiation for average individuals.Note: A daily maximum UV index of 1 in December translates into the following instructions:
Most individuals face no significant issues with extended sun exposure, but it is always essential to protect children, babies, and those with sensitive skin. Direct Sun exposure should be minimized especially during midday when radiation is most intense. Sunglasses that ward off UVA and UVB rays play a pivotal role in reducing solar eye damage. Pay attention! The reflection of snow can enhance the Sun's UV radiation almost double.
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?
How many days does it rain in December?
How much does it snow in December?
What is the month with the shortest days?
How many hours of daylight does Mercer have in December?
When are sunrise and sunset in December?
How many hours of sunshine does Mercer have in December?
What is the month with the lowest UV index?
What is the UV index intensity in December?
Average temperature in December
Mercer, PA
- Average high temperature in December: 37°F
The warmest month (with the highest average high temperature) is July (80.4°F).
The month with the lowest average high temperature is January (30.6°F).
- Average low temperature in December: 26.2°F
The month with the highest average low temperature is July (59.5°F).
The coldest month (with the lowest average low temperature) is January (18.3°F).
Average pressure in December
Mercer, PA
- Average pressure in December: 30.09"Hg
The month with the highest atmospheric pressure is November (30.12"Hg).
The month with the lowest atmospheric pressure is June (29.94"Hg).
Average wind speed in December
Mercer, PA
- Average wind speed in December: 7.6mph
The windiest month (with the highest average wind speed) is January (8.3mph).
The calmest months (with the lowest average wind speed) are July and August (5.2mph).
Average humidity in December
Mercer, PA
- Average humidity in December: 87%
The month with the highest relative humidity is February (89%).
The months with the lowest relative humidity are April, May and July (79%).
Average rainfall in December
Mercer, PA
- Average rainfall in December: 2.8"
The wettest months (with the highest rainfall) are April and June (3.74").
The driest month (with the least rainfall) is November (2.2").
Average rainfall days in December
Mercer, PA
- Average rainfall days in December: 11.3 days
The month with the highest number of rainy days is May (20.9 days).
The month with the least rainy days is January (8.3 days).
Average snowfall in December
Mercer, PA
- Average snowfall in December: 6.18"
The month with the highest snowfall is January (8.27").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in December
Mercer, PA
- Average snowfall days in December: 14.9 days
The month with the highest number of snowfall days is January (19.6 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in December /
Average sunshine in December
Mercer, PA
- Average daylight in December: 9h and 2min
The month with the longest days is June (Average daylight: 15h and 6min).
The month with the shortest days is December (Average daylight: 9h and 18min).
- Average sunshine in December: 2h and 5min
The months with the most sunshine are July and August (Average sunshine: 9h and 54min).
The month with the least sunshine is January (Average sunshine: 2h and 24min).
Average sunshine days in December
Mercer, PA
- Average sunshine days in December: 8.5 days
The month with the most sunshine days is September (14 days).
The month with the least sunshine days is February (6.2 days).
Average UV index in December
Mercer, PA
- Average UV index in December: 1
The months with the highest UV index are May, June, July and August (UV index 5).
The month with the lowest UV index is December (UV index 1).
Average cloud cover in December
Mercer, PA
- Average cloud cover in December: 70
The month with the most cloud cover is January (Cloud cover 75).
The month with the least cloud cover is August (Cloud cover 36).
Average visibility in December
Mercer, PA
- Average visibility in December: 4mi
The months with the highest visibility are March, April, May, June, July, August, September, October and November (5mi).
The months with the lowest visibility are January, February and December (4mi).
Mercer, Pennsylvania, USA
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