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
In December, the average high-temperature marginally drops from a fresh 53.6°F (12°C) in November to a frosty 45.1°F (7.3°C). The average low-temperature, in Herndon, Virginia, is 32°F (0°C).Humidity
December is the most humid month in Herndon, Virginia, with an average relative humidity of 78%.Rainfall
In December, the rain falls for 10.5 days. Throughout December, 2.68" (68mm) of precipitation is accumulated. Throughout the year, there are 158.1 rainfall days, and 31.46" (799mm) of precipitation is accumulated.Snowfall
January through April, November and December are months with snowfall. In Herndon, during 2.7 snowfall days, 1.97" (50mm) of snow is typically accumulated. In Herndon, during the entire year, snow falls for 16.7 days and aggregates up to 12.28" (312mm) of snow.Daylight
The month with the shortest days is December, with an average of 9h and 29min of daylight.On the first day of the month, sunrise is at 7:09 am and sunset at 4:47 pm. On the last day of December, sunrise is at 7:28 am and sunset at 4:56 pm EST.
Sunshine
January, February and December, with an average of 5h of sunshine, are months with the least sunshine.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 value of 2, and less, symbolizes a low health risk from unprotected exposure to Sun's UV rays for the average person.Note: In December, the average maximum UV index of 2 translate into the following recommendations:
Extended sun exposure is not an issue for the majority. Children, infants, and fair-skinned individuals always need to be protected. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects. Caution! The reflection of snow can nearly double the intensity of the Sun's UV radiation.
FAQ
What is the temperature in December in Herndon?
What is the most humid month in Herndon?
What is the average humidity in December in Herndon?
How much does it rain in Herndon in December?
How much does it snow in Herndon in December?
What is the month with the shortest days in Herndon?
What is the average length of the day in December in Herndon?
When is the sunrise / sunset in December in Herndon?
What is the month with the least sunshine in Herndon?
How long on average sun shines in December in Herndon?
What are the months with the lowest UV index in Herndon?
What is the UV index intensity in December in Herndon?
Average temperature in December
Herndon, VA
- Average high temperature in December: 45.1°F
The warmest month (with the highest average high temperature) is July (87.8°F).
The month with the lowest average high temperature is January (39.7°F).
- Average low temperature in December: 32°F
The month with the highest average low temperature is July (67.3°F).
The coldest month (with the lowest average low temperature) is January (25.9°F).
Average pressure in December
Herndon, VA
- 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
Herndon, VA
- Average wind speed in December: 6.6mph
The windiest month (with the highest average wind speed) is March (7.5mph).
The calmest month (with the lowest average wind speed) is August (4.7mph).
Average humidity in December
Herndon, VA
- Average humidity in December: 78%
The month with the highest relative humidity is December (78%).
The month with the lowest relative humidity is July (70%).
Average rainfall in December
Herndon, VA
- Average rainfall in December: 2.68"
The wettest month (with the highest rainfall) is August (3.78").
The driest month (with the least rainfall) is September (1.93").
Average rainfall days in December
Herndon, VA
- Average rainfall days in December: 10.5 days
The month with the highest number of rainy days is May (17.5 days).
The month with the least rainy days is January (9.3 days).
Average snowfall in December
Herndon, VA
- Average snowfall in December: 1.97"
The month with the highest snowfall is January (3.54").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in December
Herndon, VA
- Average snowfall days in December: 2.7 days
The months with the highest number of snowfall days are January and February (5.1 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average daylight in December /
Average sunshine in December
Herndon, VA
- Average daylight in December: 9h and 29min
The month with the longest days is June (Average daylight: 14h and 52min).
The month with the shortest days is December (Average daylight: 9h and 29min).
- Average sunshine in December: 5h and 0min
The month with the most sunshine is July (Average sunshine: 10h and 42min).
The months with the least sunshine are January, February and December (Average sunshine: 5h and 0min).
Average sunshine days in December
Herndon, VA
- Average sunshine days in December: 17.5 days
The month with the most sunshine days is November (19.5 days).
The month with the least sunshine days is July (11.8 days).
Average UV index in December
Herndon, VA
- 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
Herndon, VA
- Average cloud cover in December: 47
The month with the most cloud cover is March (Cloud cover 48).
The month with the least cloud cover is July (Cloud cover 31).
Average visibility in December
Herndon, VA
- Average visibility in December: 6mi
The months with the highest visibility are January, February, March, April, June, July, August, September, October, November and December (6mi).
The month with the lowest visibility is May (5mi).
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