December weather forecast and climate
Castle Rock, CO

The scenic setting of Castle Rock City in Colorado
The scenic setting of Castle Rock City in Colorado

Weather in December

December, the first month of the winter, in Castle Rock, is still a cold month, with temperature in the range of an average high of 39.6°F (4.2°C) and an average low of 20.1°F (-6.6°C).

Temperature

With an average high-temperature of 39.6°F (4.2°C) and an average low-temperature of 20.1°F (-6.6°C), December is the coldest month.

Humidity

In Castle Rock, the average relative humidity in December is 62%.

Rainfall

Months with the least rainfall are January and December Rain falls for 5.5 days and accumulates 0.55" (14mm) of rain.

Snowfall

Months with snowfall are January through June, October through December. In Castle Rock, during 8.4 snowfall days, 3.86" (98mm) of snow is typically accumulated. In Castle Rock, during the entire year, snow falls for 51 days, and aggregates up to 40.43" (1027mm) of snow.

Daylight

The month with the shortest days in Castle Rock, Colorado, is December, with an average of 9.4h of daylight.

Sunshine

The average sunshine in Castle Rock is 7h.

UV index

January, February, October through 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 threat to health from unsafe exposure to the UV radiation for average individuals.
Note: The daily maximum UV index of 2 interpret into the following advice:
For the majority, extended sun exposure is not of great concern. Infants and people with sensitive skin must always be protected. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects. Caution! The reflection of snow can nearly double the intensity of the Sun's UV radiation.
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FAQ

What is the coldest month in Castle Rock?

December is the coldest month, with an average high-temperature of 39.6°F (4.2°C) and an average low-temperature of 20.1°F (-6.6°C).

What is the temperature in December in Castle Rock?

In December, in Castle Rock, the average high-temperature is 39.6°F (4.2°C), and the average low-temperature is 20.1°F (-6.6°C).

What is the average humidity in December in Castle Rock?

The average relative humidity in December in Castle Rock is 62%.

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

In Castle Rock, during December, the rain falls for 5.5 days and regularly aggregates up to 0.55" (14mm) of precipitation.

What is the driest month in Castle Rock?

Months with the least rainfall in Castle Rock, Colorado, are January and December Rain falls for 5.5 days and accumulates 0.55" (14mm) of rain.

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

In Castle Rock, in December, during 8.4 snowfall days, 3.86" (98mm) of snow is typically accumulated.

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

With an average of 9.4h of daylight, December has the shortest days of the year.

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

In December, the average length of the day is 9.4h.

How many hours of sunshine does Castle Rock have in December?

In December, the average sunshine in Castle Rock is 7h.

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

Months with the lowest UV index in Castle Rock, Colorado, are January, February, October through December, with an average maximum UV index of 2.

What is the UV index intensity in December in Castle Rock?

In Castle Rock, the average daily maximum UV index in December is 2. A UV Index estimate of 2, and below, represents a minimal health vulnerability from unsafe exposure to the Sun's UV rays.

Average temperature in December
Castle Rock, CO

Average temperature in December - Castle Rock, CO
  • Average high temperature in December: 39.6°F

The warmest month (with the highest average high temperature) is July (83.3°F).
The month with the lowest average high temperature is December (39.6°F).

  • Average low temperature in December: 20.1°F

The month with the highest average low temperature is July (57.2°F).
The coldest month (with the lowest average low temperature) is December (20.1°F).

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Average pressure in December
Castle Rock, CO

Average pressure in December - Castle Rock, CO
  • Average pressure in December: 30.11"

The month with the highest atmospheric pressure is January (30.13").
Months with the lowest atmospheric pressure are April and June (29.91").

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Average wind speed in December
Castle Rock, CO

Average wind speed in December - Castle Rock, CO
  • Average wind speed in December: 6.8mph

The windiest month (with the highest average wind speed) is April (7.9mph).
The calmest months (with the lowest average wind speed) are July, August and September (6.5mph).

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Average humidity in December
Castle Rock, CO

Average humidity in December - Castle Rock, CO
  • Average humidity in December: 62%

The month with the highest relative humidity is February (66%).
Months with the lowest relative humidity are June and September (45%).

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Average rainfall in December
Castle Rock, CO

Average rainfall in December - Castle Rock, CO
  • Average rainfall in December: 0.55"

The wettest month (with the highest rainfall) is May (2.24").
The driest months (with the least rainfall) are January and December (0.55").

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Average rainfall days in December
Castle Rock, CO

Average rainfall days in December - Castle Rock, CO
  • Average rainfall days in December: 5.5 days

The month with the highest number of rainy days is July (15.1 days).
The month with the least rainy days is November (3 days).

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Average snowfall in December
Castle Rock, CO

Average snowfall in December - Castle Rock, CO
  • Average snowfall in December: 3.86"

The month with the highest snowfall is April (7.13").
Months with the least snowfall are July, August and September (0").

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Average snowfall days in December
Castle Rock, CO

Average snowfall days in December - Castle Rock, CO
  • Average snowfall days in December: 8.4 days

The month with the highest number of snowfall days is February (9.8 days).
Months with the least snowfall days are July and August (0 days).

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Average daylight in December /
Average sunshine in December
Castle Rock, CO

Average daylight in December / Average sunshine in December - Castle Rock, CO
  • Average daylight in December: 9.4h

The month with the longest days is June (Average daylight: 14.9h).
The month with the shortest days is December (Average daylight: 9.4h).

  • Average sunshine in December: 7h

Months with the most sunshine are June, July and August (Average sunshine: 11.8h).
The month with the least sunshine is February (Average sunshine: 6.8h).

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Average sunshine days in December
Castle Rock, CO

Average sunshine days in December - Castle Rock, CO
  • Average sunshine days in December: 20.5 days

The month with the most sunshine days is November (22.8 days).
The month with the least sunshine days is July (10.6 days).

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Average UV index in December
Castle Rock, CO

Average UV index in December - Castle Rock, CO
  • Average UV index in December: 2

Months with the highest UV index are June and July (UV index 6).
Months with the lowest UV index are January, February, October, November and December (UV index 2).

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Average cloud cover in December
Castle Rock, CO

Average cloud cover in December - Castle Rock, CO
  • Average cloud cover in December: 22

The month with the most cloud cover is April (Cloud cover 27).
The month with the least cloud cover is September (Cloud cover 15).

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Average visibility in December
Castle Rock, CO

Average visibility in December - Castle Rock, CO
  • Average visibility in December: 6mi

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

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