Helena
Montana, USA
Long-term weather forecast
Long-term weather forecast

December weather forecast and climate
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
The first month of the winter, December, is still a freezing cold month in Helena, Montana, with average temperature ranging between min 11.8°F (-11.2°C) and max 31.6°F (-0.2°C).

Temperature

The coldest month is December, with an average high-temperature of 31.6°F (-0.2°C) and an average low-temperature of 11.8°F (-11.2°C).

Humidity

The most humid month in Helena, Montana, is December, with an average relative humidity of 68.1%.

Rainfall

In Helena, in December, it is raining for 6.6 days, with typically 0.4" (10.2mm) of accumulated precipitation. Throughout the year, there are 91.6 rainfall days, and 11.2" (284.9mm) of precipitation is accumulated.

Snowfall

January through May, August through December are months with snowfall in Helena, Montana. December is the month with the most snowfall in Helena. Snow falls for 6 days and accumulates 7.3" (185.4mm) of snow.

Daylight

December has the shortest days of the year in Helena, with an average of 8.6h of daylight.

Sunshine

The month with the least sunshine is December, with an average of 3.2h of sunshine.

UV index

Months with the lowest UV index in Helena are January, November and December, with an average maximum UV index of 1. A UV Index estimate of 2, and below, represents a low health risk from the exposure to the Sun's UV rays for ordinary individuals.
Note: In December, the average maximum UV index of 1 translate into the following recommendations:
People with sensitive skin, children, and babies should always be protected from prolonged 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. Beware! The strength of the UV rays is increased nearly double-fold by the reflection of the snow.

What is the coldest month in Helena?

December is the coldest month, with an average high-temperature of 31.6°F (-0.2°C) and an average low-temperature of 11.8°F (-11.2°C).

What is the temperature in December in Helena?

The average high-temperature, in December, in Helena, is 31.6°F (-0.2°C), while the average low-temperature is 11.8°F (-11.2°C).

What is the most humid month in Helena?

With an average relative humidity of 68.1%, December is the most humid month in Helena.

What is the average humidity in December in Helena?

In December, the average relative humidity is 68.1%.

How many days does it rain in December in Helena?

In December, in Helena, the rain falls for 6.6 days. Throughout December, 0.4" (10.2mm) of precipitation is accumulated.

How many days does it snow in December in Helena?

In December, in Helena, Montana, it is snowing for 6 days. Throughout December, 7.3" (185.4mm) of snow is accumulated.

When does it snow the most in Helena?

December is the month with the most snowfall in Helena, Montana. Snow falls for 6 days and accumulates 7.3" (185.4mm) of snow.

What is the month with the shortest days in Helena?

With an average of 8.6h of daylight, December has the shortest days of the year in Helena.

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

In Helena, the average length of the day in December is 8.6h.

What is the month with the least sunshine in Helena?

With an average of 3.2h of sunshine, December has the least sunshine of the year in Helena.

How long on average sun shines in December in Helena?

In December, the average sunshine in Helena is 3.2h.

When is the lowest UV index in Helena?

Months with the lowest UV index in Helena are January, November and December, with an average maximum UV index of 1.

What is the UV index reading in December in Helena?

In Helena, the average daily maximum UV index in December is 1. A UV Index estimate of 2, and below, represents a minimal health vulnerability from the exposure to the Sun's UV radiation.
Average temperature in December - Helena, MT
  • Average high temperature in December: -0.2°C

The warmest month (with the highest average high temperature) is July (29.8°C).
The month with the lowest average high temperature is December (-0.2°C).

  • Average low temperature in December: -11.2°C

The month with the highest average low temperature is July (12.4°C).
The coldest month (with the lowest average low temperature) is December (-11.2°C).

Average humidity in December - Helena, MT
  • Average humidity in December: 68.1%

The month with the highest relative humidity is December (68.1%).
The month with the lowest relative humidity is July (46.4%).

Average rainfall in December - Helena, MT
  • Average rainfall in December: 10.2mm

The wettest month (with the highest rainfall) is June (52.3mm).
The driest month (with the lowest rainfall) is February (7.6mm).

Average rainfall days in December - Helena, MT
  • Average rainfall days in December: 6.6 days

The month with the highest number of rainy days is June (11.2 days).
The month with the lowest number of rainy days is February (5.9 days).

Average snowfall in December - Helena, MT
  • Average snowfall in December: 185.4mm

The month with the highest snowfall is December (185.4mm).
Months with the lowest snowfall are June and July (0mm).

Average snowfall days in December - Helena, MT
  • Average snowfall days in December: 6 days

The month with the highest number of snowfall days is December (6 days).
The month with the lowest number of snowfall days is July (0 days).

Average daylight in December / Average sunshine in December - Helena, MT
  • Average daylight in December: 8.6h

The month with the longest days is June (Average daylight: 15.8h).
The month with shortest days is December (Average daylight: 8.6h).

  • Average sunshine in December: 3.2h

The month with most sunshine is July (Average sunshine: 11.9h).
The month with least sunshine is December (Average sunshine: 3.2h).

Average UV index in December - Helena, MT
  • Average UV index in December: 1

The month with the highest UV index is July (UV index 9).
Months with the lowest UV index are January, November and December (UV index 1).