December weather forecast
Thornton, CO

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Weather in December

December, the first month of the winter in Thornton, is also an icy month, with an average temperature ranging between max 41.2°F (5.1°C) and min 21.9°F (-5.6°C).

Temperature

December, recording an average high temperature of 41.2°F (5.1°C) and a low temperature of 21.9°F (-5.6°C), is Thornton's coldest month.

Humidity

In December, the average relative humidity is 60%.

Rainfall

January and December are months with the least rain when the rain falls for 1.7 days and typically aggregates up to 0.08" (2mm) of rain.

Snowfall

Months with snowfall are January through May, October through December. In Thornton, during December, snow falls for 2 days and regularly aggregates up to 0.55" (14mm) of snow. In Thornton, during the entire year, snow falls for 19.6 days and aggregates up to 8.5" (216mm) of snow.

Daylight

With an average of 9h and 24min of daylight, December has the shortest days of the year.
On the first day of the month, sunrise is at 7:02 am and sunset at 4:35 pm. On the last day of December, sunrise is at 7:21 am and sunset at 4:45 pm MST.

Sunshine

The average sunshine in December is 7h.

UV index

The months with the lowest UV index are January, February, November and December, with an average maximum UV index of 2. A UV Index of 2, and less, symbolizes a low health risk from unsafe exposure to UV radiation for ordinary individuals.
Note: In December, a daily UV index of 2 turns into the following recommendations:
While most can endure approximately an hour in the sun without burning, children always require protection from sunlight. Exposing oneself to the midday Sun can be harmful due to the strong UV radiation; limit your time outside. Stay sun-safe with clothing that is both closely woven and worn loosely. Beware! Reflection from snow can magnify the Sun's UV radiation nearly twofold.
Updated: Aug 15, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What month is the coldest?

In Thornton, December is known for its average lowest temperatures, reaching a high of 41.2°F (5.1°C) and a low of 21.9°F (-5.6°C).

How cold is December?

In December, in Thornton, the average high-temperature is 41.2°F (5.1°C), and the average low-temperature is 21.9°F (-5.6°C). The average heat index (a.k.a. 'feels like', 'real feel'), which takes the relative humidity and factors it into the air temperature reading, in July is estimated at 89.6°F (32°C).

What is the average humidity in December?

The average relative humidity in December is 60%.

What is the driest month in Thornton?

January and December are months with the least rain when the rain falls for 1.7 days and typically aggregates up to 0.08" (2mm) of rain.

How many days does it rain in December?

In Thornton, during December, the rain falls for 1.7 days and regularly aggregates up to 0.08" (2mm) of precipitation.

How many days does it snow in December?

In December, it is snowing for 2 days. Throughout December, 0.55" (14mm) of snow is accumulated.

What is the month with the shortest days?

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

How many hours of daylight does Thornton have in December?

In Thornton, the average day length in December is 9h and 24min.

When is the sunrise / sunset in December?

On the first day of December, sunrise is at 7:02 am and sunset at 4:35 pm. On the last day of the month, sunrise is at 7:21 am and sunset at 4:45 pm MST.

How long on average sun shines in December?

The average sunshine duration in December is 7h.

When is the lowest UV index?

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

What is the UV index intensity in December?

The average daily maximum UV index in December is 2. A UV Index estimate of 2, and below, represents a low health risk 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
Thornton, CO

Average temperature in December - Thornton, CO
  • Average high temperature in December: 41.2°F

The warmest month (with the highest average high temperature) is July (88.3°F).
The month with the lowest average high temperature is December (41.2°F).

  • Average low temperature in December: 21.9°F

The month with the highest average low temperature is July (61.7°F).
The coldest month (with the lowest average low temperature) is December (21.9°F).

Average pressure in December
Thornton, CO

Average pressure in December - Thornton, CO
  • Average pressure in December: 30.12"Hg

The month with the highest atmospheric pressure is January (30.14"Hg).
The months with the lowest atmospheric pressure are April and June (29.91"Hg).

Average wind speed in December
Thornton, CO

Average wind speed in December - Thornton, CO
  • Average wind speed in December: 5.8mph

The windiest month (with the highest average wind speed) is April (6.9mph).
The calmest month (with the lowest average wind speed) is December (5.8mph).

Average humidity in December
Thornton, CO

Average humidity in December - Thornton, CO
  • Average humidity in December: 60%

The month with the highest relative humidity is February (64%).
The month with the lowest relative humidity is August (39%).

Average rainfall in December
Thornton, CO

Average rainfall in December - Thornton, CO
  • Average rainfall in December: 0.08"

The wettest month (with the highest rainfall) is July (0.59").
The driest months (with the least rainfall) are January and December (0.08").

Average rainfall days in December
Thornton, CO

Average rainfall days in December - Thornton, CO
  • Average rainfall days in December: 1.7 days

The month with the highest number of rainy days is July (8.2 days).
The month with the least rainy days is February (1.2 days).

Average snowfall in December
Thornton, CO

Average snowfall in December - Thornton, CO
  • Average snowfall in December: 0.55"

The month with the highest snowfall is October (1.42").
The months with the least snowfall are June, July, August and September (0").

Average snowfall days in December
Thornton, CO

Average snowfall days in December - Thornton, CO
  • Average snowfall days in December: 2 days

The month with the highest number of snowfall days is February (4.7 days).
The months with the least snowfall days are June, July, August and September (0 days).

Average daylight in December /
Average sunshine in December
Thornton, CO

Average daylight in December / Average sunshine in December - Thornton, CO
  • Average daylight in December: 9h and 2min

The month with the longest days is June (Average daylight: 15h and 0min).
The month with the shortest days is December (Average daylight: 9h and 24min).

  • Average sunshine in December: 7h and 0min

The months with the most sunshine are June and July (Average sunshine: 11h and 54min).
The month with the least sunshine is February (Average sunshine: 6h and 42min).

Average sunshine days in December
Thornton, CO

Average sunshine days in December - Thornton, CO
  • Average sunshine days in December: 28.5 days

The month with the most sunshine days is December (28.5 days).
The month with the least sunshine days is July (19.6 days).

Average UV index in December
Thornton, CO

Average UV index in December - Thornton, CO
  • Average UV index in December: 2

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

Average cloud cover in December
Thornton, CO

Average cloud cover in December - Thornton, CO
  • Average cloud cover in December: 22

The months with the most cloud cover are February, April and May (Cloud cover 25).
The month with the least cloud cover is September (Cloud cover 14).

Average visibility in December
Thornton, CO

Average visibility in December - Thornton, CO
  • 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).

Thornton, Colorado, USA

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