December weather forecast
Helena, MT

The State Capital building of Montana in Helena city, set on a beautiful natural park
The State Capital building of Montana in Helena city, set on a beautiful natural park

Weather in December

December, the first month of the winter in Helena, is also a subzero cold month, with temperature in the range of an average high of 27.7°F (-2.4°C) and an average low of 14.2°F (-9.9°C).

Temperature

December is the coldest month, with an average high-temperature of 27.7°F (-2.4°C) and an average low-temperature of 14.2°F (-9.9°C).

Humidity

In Helena, the average relative humidity in December is 83%.

Rainfall

The months with the least rainfall are January and December Rain falls for 7.9 days and accumulates 0.63" (16mm) of rain.

Snowfall

January through May, September through December are months with snowfall. In December, it is snowing for 14.1 days. Throughout December, 4.61" (117mm) of snow is accumulated. Throughout the year, there are 80.4 snowfall days, and 34.88" (886mm) of snow is accumulated.

Daylight

December has the shortest days of the year, with an average of 8h and 38min of daylight.
On the first day of the month, sunrise is at 7:51 am and sunset at 4:42 pm. On the last day of December, in Helena, sunrise is at 8:12 am and sunset at 4:50 pm MST.

Sunshine

In December, the average sunshine is 5.8h.

UV index

The average daily maximum UV index in December in Helena is 2. A UV Index of 2, and less, symbolizes a minimal health hazard from exposure to the Sun's UV radiation for the ordinary person.
Note: The average daily UV index of 2 in December transform into the following instructions:
Most people can stay in the Sun for up to 1 hour without burning, apart from children that always must be protected from sun exposure. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes. 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 Helena?

With an average high-temperature of 27.7°F (-2.4°C) and an average low-temperature of 14.2°F (-9.9°C), December is the coldest month in Helena.

What is the temperature in December in Helena?

In December, in Helena, the average high-temperature is 27.7°F (-2.4°C), and the average low-temperature is 14.2°F (-9.9°C).

What is the average humidity in December in Helena?

In Helena, the average relative humidity in December is 83%.

What is the driest month in Helena?

January and December are months with the least rain when the rain falls for 7.9 days and typically aggregates up to 0.63" (16mm) of rain.

How much does it rain in Helena in December?

In Helena, during December, the rain falls for 7.9 days and regularly aggregates up to 0.63" (16mm) of precipitation.

How many days does it snow in December in Helena?

In Helena, in December, during 14.1 snowfall days, 4.61" (117mm) of snow is typically accumulated.

What is the month with the shortest days in Helena?

With an average of 8h and 38min of daylight, December has the shortest days of the year.

How many hours of daylight does Helena have in December?

In Helena, the average day length in December is 8h and 38min.

When are sunrise and sunset in December in Helena?

On the first day of December in Helena, Montana, sunrise is at 7:51 am and sunset at 4:42 pm. On the last day of the month, sunrise is at 8:12 am and sunset at 4:50 pm MST.

How long on average sun shines in December in Helena?

In Helena, Montana, the average sunshine duration in December is 5.8h.

What is the UV index reading in December in Helena?

In Helena, the average daily maximum UV index in December is 2. A UV Index of 2, and less, symbolizes a minimal health vulnerability 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 December
Helena, MT

Average temperature in December - Helena, MT
  • Average high temperature in December: 27.7°F

The warmest month (with the highest average high temperature) is July (80.2°F).
The month with the lowest average high temperature is December (27.7°F).

  • Average low temperature in December: 14.2°F

The month with the highest average low temperature is July (50.4°F).
The coldest month (with the lowest average low temperature) is December (14.2°F).

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Average pressure in December
Helena, MT

Average pressure in December - Helena, MT
  • Average pressure in December: 30.17"Hg

The month with the highest atmospheric pressure is January (30.18"Hg).
The month with the lowest atmospheric pressure is June (29.9"Hg).

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Average wind speed in December
Helena, MT

Average wind speed in December - Helena, MT
  • Average wind speed in December: 6.8mph

The windiest month (with the highest average wind speed) is November (7.1mph).
The calmest month (with the lowest average wind speed) is August (5mph).

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Average humidity in December
Helena, MT

Average humidity in December - Helena, MT
  • Average humidity in December: 83%

The month with the highest relative humidity is January (85%).
The months with the lowest relative humidity are July and August (46%).

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Average rainfall in December
Helena, MT

Average rainfall in December - Helena, MT
  • Average rainfall in December: 0.63"

The wettest month (with the highest rainfall) is June (2.01").
The driest months (with the least rainfall) are January and December (0.63").

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Average rainfall days in December
Helena, MT

Average rainfall days in December - Helena, MT
  • Average rainfall days in December: 7.9 days

The month with the highest number of rainy days is May (15.8 days).
The month with the least rainy days is November (7 days).

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Average snowfall in December
Helena, MT

Average snowfall in December - Helena, MT
  • Average snowfall in December: 4.61"

The month with the highest snowfall is February (6.18").
The months with the least snowfall are June, July and August (0").

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Average snowfall days in December
Helena, MT

Average snowfall days in December - Helena, MT
  • Average snowfall days in December: 14.1 days

The month with the highest number of snowfall days is February (16.2 days).
The months with the least snowfall days are July and August (0 days).

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Average daylight in December /
Average sunshine in December
Helena, MT

Average daylight in December / Average sunshine in December - Helena, MT
  • Average daylight in December: 8h and 38min

The month with the longest days is June (Average daylight: 15h and 46min).
The month with the shortest days is December (Average daylight: 8h and 38min).

  • Average sunshine in December: 5h and 48min

The month with the most sunshine is July (Average sunshine: 11h and 42min).
The month with the least sunshine is January (Average sunshine: 5h and 36min).

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Average sunshine days in December
Helena, MT

Average sunshine days in December - Helena, MT
  • Average sunshine days in December: 15.5 days

The month with the most sunshine days is July (20.5 days).
The month with the least sunshine days is April (9.8 days).

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Average UV index in December
Helena, MT

Average UV index in December - Helena, MT
  • Average UV index in December: 2

The month with the highest UV index is July (UV index 6).
The month with the lowest UV index is February (UV index 1).

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Average cloud cover in December
Helena, MT

Average cloud cover in December - Helena, MT
  • Average cloud cover in December: 43

The month with the most cloud cover is February (Cloud cover 47).
The months with the least cloud cover are July and August (Cloud cover 15).

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Average visibility in December
Helena, MT

Average visibility in December - Helena, MT
  • Average visibility in December: 5mi

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

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