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 arrival of December suggests a slight decrease in the average high-temperature, moving from a fresh 53.4°F (11.9°C) in November to a chilly 45.3°F (7.4°C). An average minimum temperature of 32.9°F (0.5°C) marks the month of December.Humidity
With an average relative humidity of 77%, December is the most humid month.Rainfall
In December, the rain falls for 9.9 days. Throughout December, 2.44" (62mm) of precipitation is accumulated. In Rockville, Maryland, during the entire year, the rain falls for 156.4 days and collects up to 30.79" (782mm) of precipitation.Snowfall
Months with snowfall are January through April, November and December. In Rockville, in December, snow falls for 3.2 days, with typically accumulated 1.42" (36mm) of snow. In Rockville, during the entire year, snow falls for 17.7 days and aggregates up to 9.92" (252mm) of snow.Daylight
December has the shortest days of the year, with an average of 9h and 30min of daylight.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
The months with the least sunshine are January, February and December, with an average of 5.1h of sunshine.UV index
The months with the lowest UV index are January, February, November and December, with an average maximum UV index of 2. A UV Index value of 2, and less, symbolizes a minimal health hazard from exposure to the Sun's UV radiation for the average person.Note: A maximum high UV index of 2 in December translates into the following recommendations:
Apart from children, who require continuous protection, most can endure sun exposure for up to an hour without experiencing burns. When the Sun is at its strongest around midday, find shade and limit exposure. Employ a hat with a wide brim for robust protection, cutting UV exposure by half. Consider carefully! The reflective quality of snow can almost double the intensity of the Sun's UV radiation.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are December temperatures?
What is the most humid month?
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?
What is the average length of the day in December?
When are sunrise and sunset in December?
What is the month with the least sunshine?
How long on average sun shines in December?
When is the lowest UV index?
What is the UV index reading in December?
Average temperature in December
Rockville, MD
- Average high temperature in December: 45.3°F
The warmest month (with the highest average high temperature) is July (87.1°F).
The month with the lowest average high temperature is January (39°F).
- Average low temperature in December: 32.9°F
The month with the highest average low temperature is July (68.5°F).
The coldest month (with the lowest average low temperature) is January (26.2°F).
Average pressure in December
Rockville, MD
- 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
Rockville, MD
- Average wind speed in December: 7mph
The windiest month (with the highest average wind speed) is March (8mph).
The calmest month (with the lowest average wind speed) is August (5mph).
Average humidity in December
Rockville, MD
- Average humidity in December: 77%
The month with the highest relative humidity is December (77%).
The month with the lowest relative humidity is July (70%).
Average rainfall in December
Rockville, MD
- Average rainfall in December: 2.44"
The wettest month (with the highest rainfall) is August (3.9").
The driest month (with the least rainfall) is January (1.97").
Average rainfall days in December
Rockville, MD
- Average rainfall days in December: 9.9 days
The month with the highest number of rainy days is May (17.1 days).
The month with the least rainy days is November (9.2 days).
Average snowfall in December
Rockville, MD
- Average snowfall in December: 1.42"
The month with the highest snowfall is March (3.03").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in December
Rockville, MD
- Average snowfall days in December: 3.2 days
The months with the highest number of snowfall days are January and February (5.3 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
Rockville, MD
- Average daylight in December: 9h and 3min
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 1min
The month with the most sunshine is July (Average sunshine: 10h and 48min).
The months with the least sunshine are January, February and December (Average sunshine: 5h and 6min).
Average sunshine days in December
Rockville, MD
- Average sunshine days in December: 17.7 days
The month with the most sunshine days is November (19.4 days).
The month with the least sunshine days is July (12 days).
Average UV index in December
Rockville, MD
- 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
Rockville, MD
- 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
Rockville, MD
- 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).
Rockville, Maryland, USA
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