December weather forecast
New Castle, DE

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Weather in December

December in New Castle is marked by the full arrival of winter. With temperatures further dropping, weather conditions become extremely cold. Snowfall of 0.51" is recorded, welcoming the year's most festive season. As the shortest daylight hours of the year occur, New Castle's days become chilly and nights, colder. The high relative humidity keeps the temperatures from falling well below freezing.

Temperature

The onset of December introduces a moderate change in New Castle's weather, with average high-temperatures falling from November's cool 53.2°F to a chilly 44.1°F. An average low-temperature of 32.9°F is recorded during the nights in December in New Castle.

Humidity

The average relative humidity in December in New Castle is 77%.

Rainfall

In New Castle, during December, the rain falls for 8.8 days and regularly aggregates up to 1.85" of precipitation. In New Castle, during the entire year, the rain falls for 143.2 days and collects up to 21.89" of precipitation.

Snowfall

Months with snowfall in New Castle, Delaware, are January through April, November and December. In New Castle, during December, snow falls for 2.4 days and regularly aggregates up to 0.51" of snow. Throughout the year, there are 15 snowfall days, and 5.47" of snow is accumulated.

Ocean temperature

In New Castle, the average seawater temperature in December is 48.6°F.
Note: Swimming in 48.6°F poses a severe threat. Even short exposure to 55.4°F is chilling, and going below 50°F can cause breathing irregularities and intense cold shock, based on one's stamina.

Daylight

December has the shortest days of the year, with an average of 9h and 24min of daylight.
On the first day of the month, sunrise is at 7:03 am and sunset at 4:38 pm. On the last day of December, in New Castle, Delaware, sunrise is at 7:22 am and sunset at 4:47 pm EST.

Sunshine

In New Castle, the average sunshine in December is 5.1h.

UV index

The months with the lowest UV index in New Castle are January, February, November and December, with an average maximum UV index of 2. A UV Index estimate of 2, and below, represents a minimal health vulnerability from exposure to the Sun's UV radiation for average individuals.
Note: In December, a daily maximum UV index of 2 leads to the following instructions:
While most people can stay under the sun for an hour without burning, children must always be guarded against sun exposure. When the Sun's UV radiation is most intense during midday, it's best to find shade and limit exposure. Experience reduced UV exposure by about half when donning a wide-brim hat. Heed this! Snow reflection can almost augment the UV radiation of the sun by double.
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FAQ

How cold does it get in New Castle in December?

In December, the average high-temperature and low-temperature in New Castle are 44.1°F and 32.9°F respectively. In August, the average heat index (a.k.a. 'apparent temperature', 'felt air temperature'), which factors the actual air temperature with the relative humidity, is calculated to be 89.6°F.

What is the average humidity in December in New Castle?

In New Castle, Delaware, the average relative humidity in December is 77%.

How many days does it rain in December in New Castle?

In December, the rain falls for 8.8 days. Throughout December, 1.85" of precipitation is accumulated.

How many days does it snow in December in New Castle?

In December, in New Castle, Delaware, it is snowing for 2.4 days. Throughout December, 0.51" of snow is accumulated.

How cold is the water in December in New Castle?

In December, the average ocean temperature in New Castle is 48.6°F. Swimming in 48.6°F is considered life-threatening. Even a few minutes in 55.4°F water is uncomfortable, and swimming below 50°F may cause total loss of breathing control and cold shock, depending on a person's physique.

What is the month with the shortest days in New Castle?

With an average of 9h and 24min of daylight, December has the shortest days of the year.

What is the average length of the day in December in New Castle?

In December, the average day length is 9h and 25min.

What time are sunrise and sunset in December in New Castle?

In December, on the first day of the month, sunrise is at 7:03 am and sunset at 4:38 pm. On the last day of the month, sunrise is at 7:22 am and sunset at 4:47 pm EST.

How long on average sun shines in December in New Castle?

In December, the average sunshine duration is 5.1h.

What are the months with the lowest UV index in New Castle?

January, February, November and December, with an average maximum UV index of 2, are months with the lowest UV index.

How high is the UV index in December in New Castle?

The average daily maximum UV index in December is 2. A UV Index of 2, and less, symbolizes a low health risk from unprotected exposure to UV radiation.
Today
Tomorrow
Long-term
YearJFMAMJJASONDecember
Nov
December
Jan
Average high temperature
53.2°F
44.1°F
37.8°F
Average low temperature
39.6°F
32.9°F
26.1°F
Average pressure
30.13"Hg
30.1"Hg
30.09"Hg
Average wind speed
7.8mph
8.1mph
8.7mph
Average max. wind speed
8.5mph
8.8mph
9.4mph
Average wind speed gusts
12.6mph
12.9mph
13.7mph
Average humidity
74%
77%
74%
Average rainfall
1.42"
1.85"
1.38"
Average rainfall days
8
8.8
7.8
Average snowfall
0.2"
0.51"
1.69"
Average snowfall days
0.4
2.4
5.2
Average sea temperature
55.5°F
48.5°F
42.4°F
Average daylight
10h 0min
9h 2min
9h 4min
Average sunshine
5h 5min
5h 1min
5h 1min
Average sunshine days
20.1
19.1
19.3
Average UV index
2
2
2
Average cloud cover
36%
45%
44%
Average visibility
6mi
6mi
6mi

Average temperature in December
New Castle, DE

Average temperature in December - New Castle, DE
  • Average high temperature in December: 44.1°F

The warmest month (with the highest average high temperature) is July (84.9°F).
The month with the lowest average high temperature is January (37.8°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 (26.1°F).

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Average pressure in December
New Castle, DE

Average pressure in December - New Castle, DE
  • Average pressure in December: 30.1"Hg

The month with the highest atmospheric pressure is November (30.13"Hg).
The month with the lowest atmospheric pressure is June (29.94"Hg).

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Average wind speed in December
New Castle, DE

Average wind speed in December - New Castle, DE
  • Average wind speed in December: 8.1mph

The windiest months (with the highest average wind speed) are February and March (8.8mph).
The calmest month (with the lowest average wind speed) is August (5.4mph).

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Average humidity in December
New Castle, DE

Average humidity in December - New Castle, DE
  • Average humidity in December: 77%

The month with the highest relative humidity is October (78%).
The month with the lowest relative humidity is April (72%).

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Average rainfall in December
New Castle, DE

Average rainfall in December - New Castle, DE
  • Average rainfall in December: 1.85"

The wettest month (with the highest rainfall) is August (2.83").
The driest month (with the least rainfall) is January (1.38").

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Average rainfall days in December
New Castle, DE

Average rainfall days in December - New Castle, DE
  • Average rainfall days in December: 8.8 days

The month with the highest number of rainy days is May (16.8 days).
The month with the least rainy days is January (7.8 days).

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Average snowfall in December
New Castle, DE

Average snowfall in December - New Castle, DE
  • Average snowfall in December: 0.51"

The month with the highest snowfall is January (1.69").
The months with the least snowfall are May, June, July, August, September and October (0").

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Average snowfall days in December
New Castle, DE

Average snowfall days in December - New Castle, DE
  • Average snowfall days in December: 2.4 days

The month with the highest number of snowfall days is January (5.2 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).

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Average sea temperature in December
New Castle, DE

Average sea temperature in December - New Castle, DE
  • Average sea temperature in December: 48.5°F

The best month for swimming (with the highest average sea temperature) is August (76.3°F).
The coldest month (with the lowest average sea temperature) is February (40.9°F).

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Average daylight in December /
Average sunshine in December
New Castle, DE

Average daylight in December / Average sunshine in December - New Castle, DE
  • Average daylight in December: 9h and 2min

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 24min).

  • Average sunshine in December: 5h and 1min

The month with the most sunshine is July (Average sunshine: 10h and 48min).
The month with the least sunshine is February (Average sunshine: 4h and 54min).

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Average sunshine days in December
New Castle, DE

Average sunshine days in December - New Castle, DE
  • Average sunshine days in December: 19.1 days

The month with the most sunshine days is November (20.1 days).
The month with the least sunshine days is May (11.8 days).

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Average UV index in December
New Castle, DE

Average UV index in December - New Castle, DE
  • 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).

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Average cloud cover in December
New Castle, DE

Average cloud cover in December - New Castle, DE
  • Average cloud cover in December: 45

The months with the most cloud cover are February and March (Cloud cover 46).
The month with the least cloud cover is July (Cloud cover 30).

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Average visibility in December
New Castle, DE

Average visibility in December - New Castle, DE
  • Average visibility in December: 6mi

The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).

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New Castle, Delaware, USA

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