December weather forecast
Adelphi, MD

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Weather in December

The first month of the winter, December, is also a frosty month in Adelphi, Maryland, with an average temperature varying between 33.3°F (0.7°C) and 45.3°F (7.4°C).

Temperature

December reveals a small adjustment in temperature, transitioning from an average high of a cool 53.6°F (12°C) in November to a frosty 45.3°F (7.4°C). Adelphi's average low-temperature during December nights is observed to be an icy 33.3°F (0.7°C).

Humidity

May, October and December, with an average relative humidity of 75%, are the most humid months in Adelphi, Maryland.

Rainfall

In December, in Adelphi, the rain falls for 10.4 days. Throughout December, 2.44" (62mm) of precipitation is accumulated. Throughout the year, there are 154.8 rainfall days, and 30.28" (769mm) of precipitation is accumulated.

Snowfall

Months with snowfall in Adelphi are January through April, November and December. In December, it is snowing for 2.5 days. Throughout December, 1.34" (34mm) of snow is accumulated. Throughout the year, there are 15 snowfall days, and 9.17" (233mm) of snow is accumulated.

Daylight

December has the shortest days of the year, with an average of 9h and 30min of daylight.
On the first day of the month, sunrise is at 7:08 am and sunset at 4:45 pm. On the last day of December, in Adelphi, sunrise is at 7:26 am and sunset at 4:55 pm EST.

Sunshine

The average sunshine in December is 5h.

UV index

January, November and December, with an average maximum UV index of 2, are months with the lowest UV index. A UV Index reading of 2, and below, represents a low health risk from exposure to the Sun's UV radiation for the average person.
Note: An average UV index of 2 in December transforms into this advice:
Apart from children, who require continuous protection, most can endure sun exposure for up to an hour without experiencing burns. Sun's radiation is most powerful around mid-day, so it's best to limit outdoor activities during this time. Wearing sunglasses with both UVA and UVB protection effectively reduces sun-induced eye damage. Forewarned is forearmed! The Sun's UV radiation can be almost doubled in intensity by snow reflection.
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Frequently asked questions

What are December temperatures in Adelphi?

Adelphi in December has an average high-temperature of 45.3°F (7.4°C) and an average low-temperature of 33.3°F (0.7°C). The average heat index (a.k.a. 'real feel', 'apparent temperature'), which factors the actual air temperature with the relative humidity, in August is evaluated at 95°F (35°C).

What is the most humid month in Adelphi?

The months with the highest humidity are May, October and December, with an average relative humidity of 75%.

What is the average humidity in December in Adelphi?

In Adelphi, Maryland, the average relative humidity in December is 75%.

How many days does it rain in December in Adelphi?

In Adelphi, Maryland, in December, it is raining for 10.4 days, with typically 2.44" (62mm) of accumulated precipitation.

How much does it snow in Adelphi in December?

In Adelphi, in December, snow falls for 2.5 days, with typically accumulated 1.34" (34mm) of snow.

What is the month with the shortest days in Adelphi?

The month with the shortest days in Adelphi, Maryland, is December, with an average of 9h and 30min of daylight.

What is the average length of the day in December in Adelphi?

In December, the average day length in Adelphi, Maryland, is 9h and 29min.

When are sunrise and sunset in December in Adelphi?

On the first day of December in Adelphi, Maryland, sunrise is at 7:08 am and sunset at 4:45 pm. On the last day of the month, sunrise is at 7:26 am and sunset at 4:55 pm EST.

How long on average sun shines in December in Adelphi?

In December, the average sunshine duration in Adelphi, Maryland, is 5h.

What are the months with the lowest UV index in Adelphi?

The months with the lowest UV index in Adelphi, Maryland, are January, November and December, with an average maximum UV index of 2.

How high is the UV index in December in Adelphi?

In Adelphi, the average daily maximum UV index in December is 2. A UV Index reading of 2, and below, represents a minimal health vulnerability from unprotected exposure to UV radiation.
Average humidity
Average rainfall days
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in December
Adelphi, MD

Average temperature in December - Adelphi, MD
  • Average high temperature in December: 45.3°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 (39.7°F).

  • Average low temperature in December: 33.3°F

The month with the highest average low temperature is July (69.6°F).
The coldest month (with the lowest average low temperature) is January (27.1°F).

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Average pressure in December
Adelphi, MD

Average pressure in December - Adelphi, 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).

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Average wind speed in December
Adelphi, MD

Average wind speed in December - Adelphi, MD
  • Average wind speed in December: 7.1mph

The windiest month (with the highest average wind speed) is March (8.1mph).
The calmest month (with the lowest average wind speed) is August (5.2mph).

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Average humidity in December
Adelphi, MD

Average humidity in December - Adelphi, MD
  • Average humidity in December: 75%

The months with the highest relative humidity are May, October and December (75%).
The month with the lowest relative humidity is July (69%).

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Average rainfall in December
Adelphi, MD

Average rainfall in December - Adelphi, MD
  • Average rainfall in December: 2.44"

The wettest month (with the highest rainfall) is August (3.86").
The driest month (with the least rainfall) is January (1.89").

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Average rainfall days in December
Adelphi, MD

Average rainfall days in December - Adelphi, MD
  • Average rainfall days in December: 10.4 days

The month with the highest number of rainy days is May (17.7 days).
The month with the least rainy days is November (8.5 days).

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Average snowfall in December
Adelphi, MD

Average snowfall in December - Adelphi, MD
  • Average snowfall in December: 1.34"

The month with the highest snowfall is January (2.87").
The months with the least snowfall are May, June, July, August, September and October (0").

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Average snowfall days in December
Adelphi, MD

Average snowfall days in December - Adelphi, MD
  • Average snowfall days in December: 2.5 days

The month with the highest number of snowfall days is January (4.6 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).

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Average daylight in December /
Average sunshine in December
Adelphi, MD

Average daylight in December / Average sunshine in December - Adelphi, 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 0min

The month with the most sunshine is July (Average sunshine: 10h and 36min).
The month with the least sunshine is February (Average sunshine: 4h and 54min).

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Average sunshine days in December
Adelphi, MD

Average sunshine days in December - Adelphi, MD
  • Average sunshine days in December: 17.7 days

The month with the most sunshine days is November (19.5 days).
The month with the least sunshine days is May (12 days).

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Average UV index in December
Adelphi, MD

Average UV index in December - Adelphi, 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, November and December (UV index 2).

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Average cloud cover in December
Adelphi, MD

Average cloud cover in December - Adelphi, MD
  • Average cloud cover in December: 46

The month with the most cloud cover is March (Cloud cover 47).
The month with the least cloud cover is July (Cloud cover 32).

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Average visibility in December
Adelphi, MD

Average visibility in December - Adelphi, 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).

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Adelphi, Maryland, USA

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