December is one of the cooler months of the year in Great Falls, with average highs near -0.2°C and lows around -8.4°C (mean -4.3°C). It is one of the drier months, averaging 24 mm of rainfall and 78% relative humidity across the period.
December is one of the cooler months of the year in Great Falls. Across 45 years of records, the warmest December in Great Falls was 2023 — when the month averaged 1.4°C — while the coldest was 1983 at -14.4°C. Typical December days reach -0.2°C with nights near -8.4°C. The long-term trend is warming, about 0.8°C per decade.
December is one of the drier months in Great Falls, averaging 24 mm of rainfall. The wettest December on record was 1996 with 52 mm, while the driest was 2001 at 7 mm.
Relative humidity in Great Falls during December averages 78%. The most humid December was 1983 at 90%, and the least humid was 1990 at 67%.
December receives about 1.2 kWh/m²/day of solar energy in Great Falls. The sunniest Decembers were 1986 and 2001 at 1.4 kWh/m²/day, and the cloudiest was 2008 at 0.9.
Average wind speed in Great Falls during December is 3.4 m/s. The windiest December was 1991 at 4.3 m/s, while the calmest was 1983 at 2.2 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | -5.8°C | -4.2°C | -4.4°C | -4.4°C | -1.7°C | +4.1°C |
| Avg High | -1.6°C | -0.2°C | -0.3°C | -0.5°C | 2.3°C | +3.9°C |
| Avg Low | -10.0°C | -8.3°C | -8.5°C | -8.3°C | -5.7°C | +4.3°C |
| Avg Rain | 24 mm | 21 mm | 22 mm | 27 mm | 25 mm | +1 mm |
December temperatures in Great Falls have risen by about 5.5°C between 1981–1985 and 2021–2025.
December has ranged from a record low of -38.9°C (1983) to a record high of 15.3°C (2021).
Rainfall in December is one of the drier months, averaging 24 mm, with a wettest year of 52 mm.
A quieter season to visit Great Falls
If your dates are flexible, the more temperate months of July and August tend to be the most comfortable for visiting Great Falls. That said, December — with days averaging -0.2°C and nights around -8.4°C (mean -4.3°C) and low rainfall (24 mm) — can still be rewarding for travellers who don't mind the cooler conditions, and often means fewer crowds.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 4.6°C | 0.3°C | -4.0°C | 9.9°C | -15.4°C | 39 mm | 76% | 3.7 m/s | — |
| 2024 | 4.7°C | 1.1°C | -2.5°C | 8.7°C | -8.4°C | 22 mm | 74% | 3.1 m/s | 1.1 |
| 2023 🔥 | 5.1°C | 1.4°C | -2.4°C | 12.6°C | -8.3°C | 11 mm | 75% | 3.2 m/s | 1.3 |
| 2022 | -3.8°C | -8.1°C | -12.5°C | 6.4°C | -35.1°C | 34 mm | 84% | 2.8 m/s | 1.3 |
| 2021 | -0.4°C | -4.7°C | -9.0°C | 15.3°C | -24.4°C | 30 mm | 74% | 3.4 m/s | 1 |
| 2020 | 3.6°C | -0.1°C | -3.9°C | 8.6°C | -9.4°C | 12 mm | 71% | 3.6 m/s | 1.3 |
| 2019 | 2.6°C | -1.1°C | -4.8°C | 9.2°C | -10.9°C | 16 mm | 79% | 3.2 m/s | 1.2 |
| 2018 | 1.3°C | -2.5°C | -6.2°C | 6.6°C | -16.1°C | 14 mm | 73% | 3.6 m/s | 1.2 |
| 2017 | -2.1°C | -6.1°C | -10.1°C | 6.2°C | -27.5°C | 45 mm | 77% | 2.9 m/s | 1.1 |
| 2016 | -5.2°C | -9.0°C | -12.7°C | 4.6°C | -28.4°C | 25 mm | 80% | 3.5 m/s | 1.1 |
| 2015 | 0.0°C | -3.7°C | -7.4°C | 9.9°C | -17.1°C | 32 mm | 82% | 3.2 m/s | 1.1 |
| 2014 | 1.3°C | -2.5°C | -6.3°C | 10.8°C | -26.8°C | 34 mm | 83% | 3.2 m/s | 1.1 |
| 2013 | -3.2°C | -7.0°C | -10.8°C | 5.6°C | -27.2°C | 35 mm | 79% | 3.6 m/s | 1 |
| 2012 | 0.5°C | -3.7°C | -8.0°C | 11.6°C | -18.2°C | 18 mm | 75% | 3.4 m/s | 1.2 |
| 2011 | 1.2°C | -2.9°C | -7.1°C | 8.8°C | -15.4°C | 16 mm | 76% | 3.9 m/s | 1.2 |
| 2010 | -1.2°C | -5.4°C | -9.5°C | 5.0°C | -20.4°C | 38 mm | 88% | 3 m/s | 1.2 |
| 2009 | -5.4°C | -9.4°C | -13.3°C | 3.4°C | -23.6°C | 34 mm | 83% | 2.9 m/s | 1.2 |
| 2008 | -4.6°C | -8.9°C | -13.2°C | 7.0°C | -28.5°C | 44 mm | 80% | 3.3 m/s | 0.9 |
| 2007 | 0.2°C | -3.8°C | -7.7°C | 8.8°C | -15.3°C | 12 mm | 71% | 3.7 m/s | 1.2 |
| 2006 | 1.9°C | -1.9°C | -5.7°C | 6.8°C | -13.6°C | 20 mm | 75% | 3.6 m/s | 1.2 |
| 2005 | -1.5°C | -6.0°C | -10.4°C | 8.5°C | -26.6°C | 23 mm | 87% | 3.3 m/s | 1.2 |
| 2004 | 2.7°C | -1.5°C | -5.7°C | 10.5°C | -18.4°C | 20 mm | 74% | 3.6 m/s | 1.1 |
| 2003 | 2.2°C | -1.8°C | -5.8°C | 10.0°C | -19.0°C | 32 mm | 76% | 3.1 m/s | 1.3 |
| 2002 | 3.1°C | -0.9°C | -5.0°C | 10.1°C | -12.2°C | 13 mm | 74% | 3 m/s | 1.2 |
| 2001 | 0.7°C | -3.3°C | -7.2°C | 5.5°C | -15.8°C | 7 mm | 72% | 3.2 m/s | 1.4 |
| 2000 | -1.9°C | -6.7°C | -11.5°C | 5.9°C | -23.7°C | 16 mm | 82% | 2.7 m/s | 1.2 |
| 1999 | 3.0°C | -0.5°C | -4.1°C | 6.4°C | -9.7°C | 16 mm | 70% | 4 m/s | 1.2 |
| 1998 | -0.6°C | -4.6°C | -8.7°C | 8.9°C | -24.7°C | 21 mm | 72% | 3.9 m/s | 1.2 |
| 1997 | 1.8°C | -2.2°C | -6.3°C | 7.2°C | -10.5°C | 10 mm | 73% | 3.6 m/s | 1.3 |
| 1996 🌧️ | -3.7°C | -8.0°C | -12.3°C | 4.1°C | -30.9°C | 52 mm | 87% | 3.4 m/s | 1.1 |
| 1995 | 1.0°C | -3.4°C | -7.8°C | 8.9°C | -23.0°C | 19 mm | 78% | 3 m/s | 1.3 |
| 1994 | 1.2°C | -2.8°C | -6.7°C | 7.0°C | -16.0°C | 13 mm | 74% | 3.6 m/s | 1.2 |
| 1993 | 1.1°C | -2.3°C | -5.6°C | 7.1°C | -9.7°C | 24 mm | 78% | 3.6 m/s | 1.2 |
| 1992 | -3.0°C | -7.4°C | -11.9°C | 3.7°C | -29.2°C | 22 mm | 76% | 3.5 m/s | 1.2 |
| 1991 | 1.6°C | -2.4°C | -6.3°C | 5.4°C | -12.0°C | 14 mm | 77% | 4.3 m/s | 1.3 |
| 1990 | -4.1°C | -8.6°C | -13.2°C | 8.0°C | -31.5°C | 22 mm | 67% | 4.2 m/s | 1.2 |
| 1989 | -1.0°C | -5.2°C | -9.3°C | 7.8°C | -31.5°C | 49 mm | 84% | 3.3 m/s | 1 |
| 1988 | 0.5°C | -3.7°C | -7.9°C | 7.0°C | -19.2°C | 25 mm | 74% | 3.5 m/s | 1.2 |
| 1987 | 1.3°C | -2.7°C | -6.8°C | 12.0°C | -19.6°C | 14 mm | 70% | 3.6 m/s | 1.2 |
| 1986 | 1.2°C | -2.8°C | -6.8°C | 6.0°C | -13.0°C | 9 mm | 76% | 3.5 m/s | 1.4 |
| 1985 | -2.1°C | -6.4°C | -10.8°C | 2.4°C | -24.9°C | 15 mm | 88% | 3.4 m/s | 1.1 |
| 1984 | -4.2°C | -8.9°C | -13.6°C | 4.4°C | -25.6°C | 33 mm | 80% | 3.1 m/s | 1.1 |
| 1983 ❄️ | -9.3°C | -14.4°C | -19.5°C | 2.0°C | -38.9°C | 27 mm | 90% | 2.2 m/s | — |
| 1982 | -0.6°C | -4.2°C | -7.9°C | 5.7°C | -16.6°C | 30 mm | 79% | 3.5 m/s | — |
| 1981 | 0.0°C | -3.8°C | -7.7°C | 6.6°C | -18.2°C | 14 mm | 75% | 3.1 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around -0.2°C with lows near -8.4°C (mean -4.3°C), based on 45 years of NASA POWER data.
December averages 24 mm of rainfall in Great Falls, one of the drier months. The wettest on record was 52 mm in 1996.
The hottest December reached 15.3°C in 2021. The coldest dipped to -38.9°C in 1983.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 5.5°C. Daytime highs moved from -3.2°C to 2°C and overnight lows from -11.9°C to -6.1°C over the same span.
December is one of the cooler months of the year in Great Falls and one of the drier months, so plan for around -0.2°C daytime highs and -8.4°C at night.
Not quite — December is the 2nd coolest month in Great Falls, averaging -4.3°C.
For December in Great Falls, pack warm layers and a jacket for chilly mornings, with typical highs of -0.2°C and lows of -8.4°C.
Relative humidity in December averages 78% — quite humid.
Average wind speed in December is 3.4 m/s. The windiest December on record averaged 4.3 m/s (1991).
The wettest December on record was 1996 with 52 mm. On average, December sees 24 mm.
All figures are derived from NASA POWER (Prediction Of Worldwide Energy Resources), based on MERRA-2 satellite reanalysis, covering 1981–2025.
Explore how the weather in Great Falls behaves each December, based on 45 years of NASA POWER climate data from 1981 to 2025. This page breaks down average temperatures, rainfall, humidity, wind and solar radiation for December specifically, along with year-by-year records and how the month has changed over the decades.
