December weather forecast
Castlewood, SD

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Weather in December

December, the first month of the winter in Castlewood, is also a subzero cold month, with temperature in the range of an average low of 12.4°F (-10.9°C) and an average high of 23.7°F (-4.6°C).

Temperature

Castlewood's December weather is marked by a distinct drop in high-temperatures, declining from an icy 40.1°F (4.5°C) in November to a freezing cold 23.7°F (-4.6°C). The nights of December anticipate an average low-temperature of 12.4°F (-10.9°C).

Humidity

In December, the average relative humidity is 87%.

Rainfall

In Castlewood, during December, the rain falls for 3.5 days and regularly aggregates up to 0.75" (19mm) of precipitation. In Castlewood, during the entire year, the rain falls for 112.3 days and collects up to 18.78" (477mm) of precipitation.

Snowfall

Months with snowfall are January through May, October through December. The months with the most snowfall are January and December, with an average 3.74" (95mm) of accumulated snow.

Daylight

With an average of 8h and 54min of daylight, December has the shortest days of the year.
On the first day of December, sunrise is at 7:45 am and sunset at 4:48 pm. On the last day of the month, sunrise is at 8:05 am and sunset at 4:57 pm CST.

Sunshine

In December, the average sunshine is 4h.

UV index

January and December, with an average maximum UV index of 1, are months with the lowest UV index in Castlewood. 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: In December, the average maximum UV index of 1 translates into the following recommendations:
Extended exposure to the sun should always be avoided by children, infants, and those with sensitive skin. Direct Sun exposure should be minimized especially during midday when radiation is most intense. Always opt for UVA and UVB-resistant sunglasses on radiant days. Be informed! The Sun's UV radiation can be nearly doubled due to the reflection from snow.
Updated: Aug 12, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

How cold is it in December?

The average high-temperature, in December, in Castlewood, is 23.7°F (-4.6°C), while the average low-temperature is 12.4°F (-10.9°C). In July, the average heat index (a.k.a. 'real feel', 'felt air temperature'), which factors the actual air temperature with the relative humidity, is estimated at 84.2°F (29°C).

What is the average humidity in December?

In Castlewood, the average relative humidity in December is 87%.

How many days does it rain in December?

In December, the rain falls for 3.5 days. Throughout December, 0.75" (19mm) of precipitation is accumulated.

When does it snow the most?

The months with the most snowfall are January and December, with an average 3.74" (95mm) of accumulated snow.

How much does it snow in December?

In Castlewood, South Dakota, during December, snow falls for 13 days and regularly aggregates up to 3.74" (95mm) of snow.

What is the month with the shortest days?

December has the shortest days of the year, with an average of 8h and 54min of daylight.

How many hours of daylight does Castlewood have in December?

The average day length in December is 8h and 52min.

What time are sunrise and sunset in December?

In December, on the first day of the month, sunrise is at 7:45 am and sunset at 4:48 pm. On the last day of the month, sunrise is at 8:05 am and sunset at 4:57 pm CST.

How long on average sun shines in December?

The average sunshine duration in December in Castlewood is 4h.

What is the month with the lowest UV index?

The months with the lowest UV index are January and December, with an average maximum UV index of 1.

What is the UV index reading in December?

The average daily maximum UV index in December is 1. A UV Index value of 2, and less, symbolizes a minimal health vulnerability from exposure to the Sun's 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
Castlewood, SD

Average temperature in December - Castlewood, SD
  • Average high temperature in December: 23.7°F

The warmest month (with the highest average high temperature) is July (80.8°F).
The month with the lowest average high temperature is January (19.4°F).

  • Average low temperature in December: 12.4°F

The month with the highest average low temperature is July (60.8°F).
The coldest month (with the lowest average low temperature) is January (5.5°F).

Average pressure in December
Castlewood, SD

Average pressure in December - Castlewood, SD
  • Average pressure in December: 30.13"Hg

The months with the highest atmospheric pressure are January and February (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.85"Hg).

Average wind speed in December
Castlewood, SD

Average wind speed in December - Castlewood, SD
  • Average wind speed in December: 11mph

The windiest month (with the highest average wind speed) is April (11.6mph).
The calmest month (with the lowest average wind speed) is July (8.5mph).

Average humidity in December
Castlewood, SD

Average humidity in December - Castlewood, SD
  • Average humidity in December: 87%

The month with the highest relative humidity is January (90%).
The months with the lowest relative humidity are September and October (68%).

Average rainfall in December
Castlewood, SD

Average rainfall in December - Castlewood, SD
  • Average rainfall in December: 0.75"

The wettest month (with the highest rainfall) is June (3.19").
The driest months (with the least rainfall) are January and February (0.59").

Average rainfall days in December
Castlewood, SD

Average rainfall days in December - Castlewood, SD
  • Average rainfall days in December: 3.5 days

The month with the highest number of rainy days is June (17.2 days).
The month with the least rainy days is February (2.7 days).

Average snowfall in December
Castlewood, SD

Average snowfall in December - Castlewood, SD
  • Average snowfall in December: 3.74"

The months with the highest snowfall are January and December (3.74").
The months with the least snowfall are June, July, August and September (0").

Average snowfall days in December
Castlewood, SD

Average snowfall days in December - Castlewood, SD
  • Average snowfall days in December: 13 days

The month with the highest number of snowfall days is January (14.4 days).
The months with the least snowfall days are June, July and August (0 days).

Average daylight in December /
Average sunshine in December
Castlewood, SD

Average daylight in December / Average sunshine in December - Castlewood, SD
  • Average daylight in December: 8h and 5min

The month with the longest days is June (Average daylight: 15h and 30min).
The month with the shortest days is December (Average daylight: 8h and 54min).

  • Average sunshine in December: 4h and 0min

The month with the most sunshine is July (Average sunshine: 10h and 42min).
The month with the least sunshine is January (Average sunshine: 3h and 36min).

Average sunshine days in December
Castlewood, SD

Average sunshine days in December - Castlewood, SD
  • Average sunshine days in December: 16.3 days

The month with the most sunshine days is October (19.1 days).
The month with the least sunshine days is June (10.3 days).

Average UV index in December
Castlewood, SD

Average UV index in December - Castlewood, SD
  • Average UV index in December: 1

The months with the highest UV index are June and July (UV index 6).
The months with the lowest UV index are January and December (UV index 1).

Average cloud cover in December
Castlewood, SD

Average cloud cover in December - Castlewood, SD
  • Average cloud cover in December: 59

The month with the most cloud cover is January (Cloud cover 63).
The month with the least cloud cover is August (Cloud cover 27).

Average visibility in December
Castlewood, SD

Average visibility in December - Castlewood, SD
  • Average visibility in December: 6mi

The months with the highest visibility are February, March, April, May, June, July, August, September, October, November and December (6mi).
The month with the lowest visibility is January (5mi).

Castlewood, South Dakota, USA

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