January weather forecast
Castle Rock, CO

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

Weather in January

The month of January in Castle Rock, Colorado, is the start of winter with temperatures reaching a high of 40.1°F (4.5°C) and a low of 20.8°F (-6.2°C). This month is well-known for its persisting chilly vibe but less extreme than the following month. January is characterized by snowy landscapes, as significant snowfall decorates the city. Nicely coated with the beginnings of the winter snow, January also seems to cast a calm over the city. The amount of daylight is noticeably short due to the onset of winter.

Temperature

Castle Rock, Colorado, registers an average high-temperature of a still wintry 40.1°F (4.5°C) at the commencement of January, closely related to the preceding month. Throughout January, the nighttime temperature in Castle Rock averages to a freezing cold 20.8°F (-6.2°C).

Humidity

The average relative humidity in January is 65%.

Rainfall

The months with the least rainfall are January and December Rain falls for 5.1 days and accumulates 0.55" (14mm) of rain.

Snowfall

Months with snowfall in Castle Rock are January through June, October through December. In Castle Rock, in January, snow falls for 7.6 days, with typically accumulated 4.02" (102mm) of snow. Throughout the year, there are 51 snowfall days, and 40.43" (1027mm) of snow is accumulated.

Daylight

In January, the average length of the day is 9h and 46min.
On the first day of January in Castle Rock, sunrise is at 7:19 am and sunset at 4:46 pm. On the last day of the month, sunrise is at 7:07 am and sunset at 5:18 pm MST.

Sunshine

In January, the average sunshine is 7h.

UV index

The months with the lowest UV index are January, February, October through December, with an average maximum UV index of 2. A UV Index estimate of 2, and below, represents a low threat to health from exposure to the Sun's UV rays for the average person.
Note: The maximum UV index of 2 during January leads to these instructions:
Prolonged sun exposure should always be prevented in babies, children, and those with sensitive skin. The most potent solar radiation is around mid-day, so one should minimize exposure to direct sunlight during this period. Boost your sun resistance with garments that are densely woven yet spacious. Note this! The Sun's UV radiation can nearly be doubled by the reflection off snow.
Updated: Feb 10, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

How cold does it get in Castle Rock in January?

The average high-temperature, in January, in Castle Rock, is 40.1°F (4.5°C), while the average low-temperature is 20.8°F (-6.2°C).

What is the average humidity in January in Castle Rock?

In Castle Rock, Colorado, the average relative humidity in January is 65%.

What is the driest month in Castle Rock?

The months with the least rainfall in Castle Rock, Colorado, are January and December Rain falls for 5.1 days and accumulates 0.55" (14mm) of rain.

How much does it rain in Castle Rock in January?

In January, in Castle Rock, Colorado, the rain falls for 5.1 days. Throughout January, 0.55" (14mm) of precipitation is accumulated.

How much does it snow in Castle Rock in January?

In Castle Rock, in January, during 7.6 snowfall days, 4.02" (102mm) of snow is typically accumulated.

How many hours of daylight does Castle Rock have in January?

In Castle Rock, Colorado, the average day length in January is 9h and 46min.

When are sunrise and sunset in January in Castle Rock?

On the first day of January in Castle Rock, sunrise is at 7:19 am and sunset at 4:46 pm. On the last day of the month, sunrise is at 7:07 am and sunset at 5:18 pm MST.

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

In January, the average sunshine duration is 7h.

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

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

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

The average daily maximum UV index in January in Castle Rock is 2. A UV Index reading of 2, and below, represents a minimal hazard to health from exposure to Sun's UV rays.
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 January
Castle Rock, CO

Average temperature in January - Castle Rock, CO
  • Average high temperature in January: 40.1°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 January: 20.8°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).

Average pressure in January
Castle Rock, CO

Average pressure in January - Castle Rock, CO
  • Average pressure in January: 30.13"Hg

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

Average wind speed in January
Castle Rock, CO

Average wind speed in January - Castle Rock, CO
  • Average wind speed in January: 7mph

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).

Average humidity in January
Castle Rock, CO

Average humidity in January - Castle Rock, CO
  • Average humidity in January: 65%

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

Average rainfall in January
Castle Rock, CO

Average rainfall in January - Castle Rock, CO
  • Average rainfall in January: 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").

Average rainfall days in January
Castle Rock, CO

Average rainfall days in January - Castle Rock, CO
  • Average rainfall days in January: 5.1 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).

Average snowfall in January
Castle Rock, CO

Average snowfall in January - Castle Rock, CO
  • Average snowfall in January: 4.02"

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

Average snowfall days in January
Castle Rock, CO

Average snowfall days in January - Castle Rock, CO
  • Average snowfall days in January: 7.6 days

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

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

Average daylight in January / Average sunshine in January - Castle Rock, CO
  • Average daylight in January: 9h and 5min

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 January: 7h and 0min

The months with the most sunshine are June, July and August (Average sunshine: 11h and 48min).
The month with the least sunshine is February (Average sunshine: 6h and 48min).

Average sunshine days in January
Castle Rock, CO

Average sunshine days in January - Castle Rock, CO
  • Average sunshine days in January: 21.5 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).

Average UV index in January
Castle Rock, CO

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

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

Average cloud cover in January
Castle Rock, CO

Average cloud cover in January - Castle Rock, CO
  • Average cloud cover in January: 21

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

Average visibility in January
Castle Rock, CO

Average visibility in January - Castle Rock, CO
  • Average visibility in January: 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).

Castle Rock, Colorado, USA

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