December weather forecastMcLean, VA
December
Weather in December
December, the first month of the winter in McLean, is still a chilly month, with an average temperature fluctuating between 45.5°F (7.5°C) and 33.1°F (0.6°C).Temperature
The advent of December brings a slight shift in average high-temperature, moving from a fresh 54.1°F (12.3°C) in November to a chilly 45.5°F (7.5°C). McLean, during the month of December, experiences an average low-temperature of 33.1°F (0.6°C).Humidity
The months with the highest humidity are October and December, with an average relative humidity of 76%.Rainfall
In McLean, in December, during 6.9 rainfall days, 0.67" (17mm) of precipitation is typically accumulated. Throughout the year, there are 109 rainfall days, and 9.29" (236mm) of precipitation is accumulated.Snowfall
Months with snowfall are January through April, November and December. In December, it is snowing for 1.2 days. Throughout December, 0.28" (7mm) of snow is accumulated. Throughout the year, there are 10.3 snowfall days, and 2.28" (58mm) of snow is accumulated.Daylight
With an average of 9h and 30min of daylight, December has the shortest days of the year.On the first day of December, sunrise is at 7:09 am and sunset at 4:46 pm. On the last day of the month, sunrise is at 7:27 am and sunset at 4:56 pm EST.
Sunshine
February and December, with an average of 5.1h of sunshine, are months with the least sunshine.UV index
January, November and December, with an average maximum UV index of 2, are months with the lowest UV index. A UV Index of 2, and less, symbolizes a minimal health hazard from exposure to the Sun's UV rays for the ordinary person.Note: The UV index of 2 during December leads to these advisories:
While sun exposure does not greatly affect most, individuals with fair skin, babies, and children always need vigilant safeguarding. Around midday, solar radiation is most harmful; hence, exposure should be limited. During bright days, sunglasses that offer UVA and UVB defense are recommended. Bear in mind! The Sun's UV radiation can nearly double in intensity due to the reflective quality of snow.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
McLean, VA
- Average high temperature in December: 45.5°F
The warmest month (with the highest average high temperature) is July (87.4°F).
The month with the lowest average high temperature is January (40.1°F).
- Average low temperature in December: 33.1°F
The month with the highest average low temperature is July (69.1°F).
The coldest month (with the lowest average low temperature) is January (26.8°F).
Average pressure in December
McLean, 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
McLean, VA
- Average wind speed in December: 6.8mph
The windiest month (with the highest average wind speed) is March (7.7mph).
The calmest month (with the lowest average wind speed) is August (4.9mph).
Average humidity in December
McLean, VA
- Average humidity in December: 76%
The months with the highest relative humidity are October and December (76%).
The month with the lowest relative humidity is July (70%).
Average rainfall in December
McLean, VA
- Average rainfall in December: 0.67"
The wettest month (with the highest rainfall) is August (1.5").
The driest months (with the least rainfall) are January and September (0.51").
Average rainfall days in December
McLean, VA
- Average rainfall days in December: 6.9 days
The month with the highest number of rainy days is July (13.5 days).
The month with the least rainy days is November (5.6 days).
Average snowfall in December
McLean, VA
- Average snowfall in December: 0.28"
The month with the highest snowfall is January (0.98").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in December
McLean, VA
- Average snowfall days in December: 1.2 days
The month with the highest number of snowfall days is February (3.6 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
McLean, VA
- Average daylight in December: 9h and 30min
The month with the longest days is June (Average daylight: 14h and 54min).
The month with the shortest days is December (Average daylight: 9h and 30min).
- Average sunshine in December: 5h and 6min
The month with the most sunshine is July (Average sunshine: 10h and 54min).
The months with the least sunshine are February and December (Average sunshine: 5h and 6min).
Average sunshine days in December
McLean, VA
- Average sunshine days in December: 22 days
The month with the most sunshine days is November (23 days).
The month with the least sunshine days is July (14.3 days).
Average UV index in December
McLean, 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, November and December (UV index 2).
Average cloud cover in December
McLean, VA
- Average cloud cover in December: 45
The month with the most cloud cover is March (Cloud cover 46).
The month with the least cloud cover is July (Cloud cover 30).
Average visibility in December
McLean, 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).
