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 shift to December brings a decrease in the average high-temperature, falling from a chilly 49.3°F (9.6°C) in November to a wintry 39.7°F (4.3°C). In Rosslyn Farms, December's nights observe an average temperature dip to a subzero cold 28.4°F (-2°C).Humidity
In Rosslyn Farms, the average relative humidity in December is 83%.Rainfall
In Rosslyn Farms, in December, it is raining for 8.2 days, with typically 0.87" (22mm) of accumulated precipitation. Throughout the year, there are 132.6 rainfall days, and 11.5" (292mm) of precipitation is accumulated.Snowfall
Months with snowfall are January through April, November and December. In December, it is snowing for 6.4 days. Throughout December, 0.59" (15mm) of snow is accumulated. Throughout the year, there are 32.5 snowfall days, and 3.66" (93mm) of snow is accumulated.Daylight
The month with the shortest days in Rosslyn Farms is December, with an average of 9h and 18min of daylight.On the first day of December, sunrise is at 7:24 am and sunset at 4:54 pm. On the last day of the month, sunrise is at 7:43 am and sunset at 5:04 pm EST.
Sunshine
The average sunshine in December is 3.4h.UV index
The month with the lowest UV index in Rosslyn Farms is December, with an average maximum UV index of 1. A UV Index estimate of 2, and below, represents a low threat to health from unsafe exposure to UV radiation for ordinary individuals.Note: The daily maximum UV index of 1 in December interprets into the following advice:
People with sensitive skin, children, and babies should always be protected from prolonged sun exposure. Avoiding the Sun's peak radiation during midday hours is essential for health and safety. Always opt for UVA and UVB-resistant sunglasses on radiant days. Take into account! The reflection from snow can nearly double the Sun's UV radiation intensity.
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 much 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 Rosslyn Farms have in December?
When are sunrise and sunset in December?
How many hours of sunshine does Rosslyn Farms have in December?
What is the month with the lowest UV index?
How high is the UV index in December?
Average temperature in December
Rosslyn Farms, PA
- Average high temperature in December: 39.7°F
The warmest month (with the highest average high temperature) is July (83.7°F).
The month with the lowest average high temperature is January (33.4°F).
- Average low temperature in December: 28.4°F
The month with the highest average low temperature is July (62.2°F).
The coldest month (with the lowest average low temperature) is January (21°F).
Average pressure in December
Rosslyn Farms, PA
- Average pressure in December: 30.11"Hg
The month with the highest atmospheric pressure is November (30.13"Hg).
The month with the lowest atmospheric pressure is June (29.95"Hg).
Average wind speed in December
Rosslyn Farms, PA
- Average wind speed in December: 7.3mph
The windiest month (with the highest average wind speed) is January (7.9mph).
The calmest months (with the lowest average wind speed) are July and August (4.7mph).
Average humidity in December
Rosslyn Farms, PA
- Average humidity in December: 83%
The month with the highest relative humidity is February (85%).
The months with the lowest relative humidity are July and August (75%).
Average rainfall in December
Rosslyn Farms, PA
- Average rainfall in December: 0.87"
The wettest month (with the highest rainfall) is July (1.34").
The driest month (with the least rainfall) is November (0.67").
Average rainfall days in December
Rosslyn Farms, PA
- Average rainfall days in December: 8.2 days
The month with the highest number of rainy days is July (15.6 days).
The month with the least rainy days is February (6.4 days).
Average snowfall in December
Rosslyn Farms, PA
- Average snowfall in December: 0.59"
The month with the highest snowfall is February (0.98").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in December
Rosslyn Farms, PA
- Average snowfall days in December: 6.4 days
The month with the highest number of snowfall days is January (9.3 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
Rosslyn Farms, 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 18min).
- Average sunshine in December: 3h and 2min
The month with the most sunshine is August (Average sunshine: 10h and 12min).
The month with the least sunshine is January (Average sunshine: 3h and 0min).
Average sunshine days in December
Rosslyn Farms, PA
- Average sunshine days in December: 18.5 days
The month with the most sunshine days is November (19.6 days).
The month with the least sunshine days is May (12.2 days).
Average UV index in December
Rosslyn Farms, PA
- Average UV index in December: 1
The months with the highest UV index are June, July and August (UV index 6).
The month with the lowest UV index is December (UV index 1).
Average cloud cover in December
Rosslyn Farms, PA
- Average cloud cover in December: 64
The month with the most cloud cover is January (Cloud cover 68).
The month with the least cloud cover is August (Cloud cover 33).
Average visibility in December
Rosslyn Farms, 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).
Rosslyn Farms, Pennsylvania, USA
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