December weather forecast
Longmont, CO

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Weather in December

December manifests the winter season in its entire splendor in Longmont. As temperatures drop further, the city experiences an increment in snow accumulation up to 3.03" (77mm) over 6.1 days relative to its predecessor. As the year concludes, the city gleams under the holiday lights, reclining under a fresh blanket of snow. Embracing the cold, Longmont eagerly anticipates another cycle of dramatic weather changes in the forthcoming year.

Temperature

With average high temperatures of 39°F (3.9°C) and lows of 19.9°F (-6.7°C), December is the coldest month.

Humidity

In Longmont, Colorado, the average relative humidity in December is 63%.

Rainfall

In December, in Longmont, the rain falls for 4.7 days. Throughout December, 0.39" (10mm) of precipitation is accumulated. Throughout the year, in Longmont, there are 105.4 rainfall days, and 10.43" (265mm) of precipitation is accumulated.

Snowfall

January through May, October through December are months with snowfall in Longmont. In Longmont, in December, snow falls for 6.1 days, with typically accumulated 3.03" (77mm) of snow. In Longmont, during the entire year, snow falls for 37.1 days and aggregates up to 26.73" (679mm) 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 7:04 am and sunset at 4:35 pm. On the last day of December, in Longmont, sunrise is at 7:22 am and sunset at 4:44 pm MST.

Sunshine

In Longmont, the average sunshine in December is 6.9h.

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 reading of 2, and below, represents a low health risk from exposure to the Sun's UV rays for ordinary individuals.
Note: A typical high UV index of 2 in December suggests the following recommendations:
Despite the majority tolerating prolonged sun exposure, those with sensitive skin, infants, and children demand continual protection. The Sun's radiation is especially intense around midday; try to stay in shade during this period. A wide-brimmed hat is a staple for defending the face, eyes, ears, and neck from the Sun. Be advised! The UV radiation from the Sun can be almost doubled due to the reflective properties of snow.
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Frequently asked questions

What are the coldest months in Longmont?

Longmont's coldest month, December, registers temperatures that range from a high of 39°F (3.9°C) to a low of 19.9°F (-6.7°C).

How cold is December in Longmont?

Longmont in December has an average high-temperature of 39°F (3.9°C) and an average low-temperature of 19.9°F (-6.7°C). The average heat index (a.k.a. 'feels like', 'apparent temperature'), which represents the influence of relative humidity on air temperature, in August is evaluated at 84.2°F (29°C).

What is the average humidity in December in Longmont?

The average relative humidity in December is 63%.

How many days does it rain in December in Longmont?

In Longmont, Colorado, in December, it is raining for 4.7 days, with typically 0.39" (10mm) of accumulated precipitation.

How much does it snow in Longmont in December?

In Longmont, Colorado, in December, snow falls for 6.1 days, with typically accumulated 3.03" (77mm) of snow.

What is the month with the shortest days in Longmont?

December has the shortest days of the year in Longmont, Colorado, with an average of 9h and 24min of daylight.

What is the average length of the day in December in Longmont?

In Longmont, the average day length in December is 9h and 22min.

When is the sunrise / sunset in December in Longmont?

In December, on the first day of the month, sunrise is at 7:04 am and sunset at 4:35 pm. On the last day of the month, sunrise is at 7:22 am and sunset at 4:44 pm MST.

How long on average sun shines in December in Longmont?

The average sunshine duration in December is 6.9h.

When is the lowest UV index in Longmont?

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

What is the UV index intensity in December in Longmont?

In Longmont, the average daily maximum UV index in December is 2. A UV Index estimate of 2, and below, represents a minimal hazard to health from unsafe 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 December
Longmont, CO

Average temperature in December - Longmont, CO
  • Average high temperature in December: 39°F

The warmest month (with the highest average high temperature) is July (85.6°F).
The month with the lowest average high temperature is December (39°F).

  • Average low temperature in December: 19.9°F

The month with the highest average low temperature is July (59.2°F).
The coldest month (with the lowest average low temperature) is December (19.9°F).

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Average pressure in December
Longmont, CO

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

The month with the highest atmospheric pressure is January (30.15"Hg).
The months with the lowest atmospheric pressure are April and June (29.91"Hg).

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Average wind speed in December
Longmont, CO

Average wind speed in December - Longmont, CO
  • Average wind speed in December: 5.7mph

The windiest months (with the highest average wind speed) are March and April (6.6mph).
The calmest months (with the lowest average wind speed) are August and September (5.6mph).

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Average humidity in December
Longmont, CO

Average humidity in December - Longmont, CO
  • Average humidity in December: 63%

The month with the highest relative humidity is February (66%).
The month with the lowest relative humidity is August (42%).

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Average rainfall in December
Longmont, CO

Average rainfall in December - Longmont, CO
  • Average rainfall in December: 0.39"

The wettest month (with the highest rainfall) is May (1.69").
The driest month (with the least rainfall) is January (0.35").

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Average rainfall days in December
Longmont, CO

Average rainfall days in December - Longmont, CO
  • Average rainfall days in December: 4.7 days

The month with the highest number of rainy days is July (16 days).
The month with the least rainy days is January (3.5 days).

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Average snowfall in December
Longmont, CO

Average snowfall in December - Longmont, CO
  • Average snowfall in December: 3.03"

The month with the highest snowfall is November (4.41").
The months with the least snowfall are June, July, August and September (0").

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Average snowfall days in December
Longmont, CO

Average snowfall days in December - Longmont, CO
  • Average snowfall days in December: 6.1 days

The month with the highest number of snowfall days is February (7.7 days).
The months with the least snowfall days are June, July and August (0 days).

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

Average daylight in December / Average sunshine in December - Longmont, 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: 6h and 5min

The month with the most sunshine is June (Average sunshine: 11h and 54min).
The month with the least sunshine is February (Average sunshine: 6h and 48min).

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Average sunshine days in December
Longmont, CO

Average sunshine days in December - Longmont, CO
  • Average sunshine days in December: 22.5 days

The month with the most sunshine days is January (23.4 days).
The month with the least sunshine days is July (9.3 days).

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Average UV index in December
Longmont, CO

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

The months with the highest UV index are 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
Longmont, CO

Average cloud cover in December - Longmont, CO
  • Average cloud cover in December: 23

The months with the most cloud cover are April and May (Cloud cover 26).
The months with the least cloud cover are June and September (Cloud cover 16).

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Average visibility in December
Longmont, CO

Average visibility in December - Longmont, 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).

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Longmont, Colorado, USA

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