The highest day temperature in December 2025 was 62°F. The lowest night temperature was -10°F. The average values for day and night temperatures during December were 40.2°F и 29.0°F respectivly.

Most of the days in December are sunny but you can also expect cloudy and gloomy days.

Precipitation total in December for Great Falls is 0.3 in. It makes december the least rainy month of the year.

The average wind speed in December is 9.3 mph. This value is relatively stable throughout the year.

We are using day length and cloud cover information for each day of the month to calculate averages for this chart. Average sunny hours for Great Falls in December is 5.1 hours.