December is one of the cooler months of the year in Missoula, with average highs near -3°C and lows around -11.8°C (mean -7.4°C). It is a relatively wet time of year, averaging 70 mm of rainfall and 96% relative humidity across the period.
December is one of the cooler months of the year in Missoula. Across 45 years of records, the warmest Decembers in Missoula were 2023 and 2025 — when the month averaged -2.1°C — while the coldest was 1983 at -14.6°C. Typical December days reach -3°C with nights near -11.8°C. The long-term trend is warming, about 0.8°C per decade.
December is a relatively wet time of year in Missoula, averaging 70 mm of rainfall. The wettest December on record was 2025 with 176 mm, while the driest was 1985 at 20 mm.
Relative humidity in Missoula during December averages 96%. The most humid December was 1985 at 100%, and the least humid was 2002 at 91%.
December receives about 1 kWh/m²/day of solar energy in Missoula. The sunniest Decembers were 1984, 1985 and 2009 at 1.2 kWh/m²/day, and the cloudiest were 2015, 2016 and 2021, among others at 0.8.
Average wind speed in Missoula during December is 0.4 m/s. The windiest Decembers were 2018, 2019 and 2023, among others at 0.5 m/s, while the calmest were 1996, 2013 and 2021 at 0.3 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | -8.6°C | -7.7°C | -7.6°C | -7.6°C | -4.4°C | +4.2°C |
| Avg High | -3.9°C | -3.3°C | -3.2°C | -3.2°C | -0.5°C | +3.4°C |
| Avg Low | -13.2°C | -12.0°C | -12.0°C | -12.0°C | -8.4°C | +4.8°C |
| Avg Rain | 54 mm | 69 mm | 68 mm | 85 mm | 75 mm | +21 mm |
December temperatures in Missoula have risen by about 5.3°C between 1981–1985 and 2021–2025.
December has ranged from a record low of -41°C (2022) to a record high of 9.7°C (2021).
Rainfall in December is a relatively wet time of year, averaging 70 mm, with a wettest year of 176 mm.
Daytime highs and overnight lows have shifted differently — highs rose about 0.6°C per decade while lows rose 0.9°C per decade, narrowing the gap between day and night.
A quieter season to visit Missoula
If your dates are flexible, the more temperate months of July and August tend to be the most comfortable for visiting Missoula. That said, December — with days averaging -3°C and nights around -11.8°C (mean -7.4°C) and moderate rainfall (70 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 🌧️ | 1.0°C | -2.1°C | -5.2°C | 5.9°C | -15.3°C | 176 mm | 94% | 0.4 m/s | — |
| 2024 | 1.3°C | -2.3°C | -5.9°C | 4.4°C | -11.0°C | 51 mm | 92% | 0.4 m/s | 1 |
| 2023 🔥 | 1.9°C | -2.1°C | -6.2°C | 9.4°C | -12.6°C | 29 mm | 92% | 0.5 m/s | 1.1 |
| 2022 | -3.9°C | -8.7°C | -13.6°C | 0.7°C | -41.0°C | 68 mm | 98% | 0.4 m/s | 0.9 |
| 2021 | -3.2°C | -7.2°C | -11.2°C | 9.7°C | -23.7°C | 86 mm | 95% | 0.3 m/s | 0.8 |
| 2020 | -0.2°C | -4.3°C | -8.3°C | 4.6°C | -12.6°C | 40 mm | 92% | 0.4 m/s | 1.1 |
| 2019 | -0.5°C | -4.5°C | -8.5°C | 4.3°C | -14.6°C | 42 mm | 94% | 0.5 m/s | 0.9 |
| 2018 | -1.9°C | -6.3°C | -10.7°C | 3.5°C | -25.4°C | 56 mm | 94% | 0.5 m/s | 1 |
| 2017 | -3.4°C | -7.7°C | -11.9°C | 1.5°C | -27.2°C | 117 mm | 94% | 0.4 m/s | 1 |
| 2016 | -6.9°C | -12.0°C | -17.1°C | 0.0°C | -32.9°C | 99 mm | 98% | 0.4 m/s | 0.8 |
| 2015 | -2.6°C | -6.6°C | -10.6°C | 4.6°C | -19.5°C | 96 mm | 96% | 0.4 m/s | 0.8 |
| 2014 | -2.4°C | -6.4°C | -10.4°C | 3.8°C | -32.3°C | 89 mm | 98% | 0.4 m/s | 1 |
| 2013 | -5.2°C | -9.6°C | -13.9°C | 1.0°C | -29.1°C | 92 mm | 96% | 0.3 m/s | 1 |
| 2012 | -3.5°C | -7.8°C | -12.1°C | 3.5°C | -19.7°C | 98 mm | 98% | 0.4 m/s | 0.8 |
| 2011 | -2.6°C | -6.8°C | -11.0°C | 0.7°C | -17.8°C | 59 mm | 97% | 0.4 m/s | 1.1 |
| 2010 | -3.4°C | -8.4°C | -13.4°C | 0.1°C | -31.1°C | 108 mm | 99% | 0.4 m/s | 1 |
| 2009 | -6.0°C | -10.3°C | -14.6°C | 1.0°C | -25.4°C | 73 mm | 92% | 0.4 m/s | 1.2 |
| 2008 | -6.3°C | -11.1°C | -16.0°C | 4.1°C | -30.3°C | 118 mm | 97% | 0.4 m/s | 0.9 |
| 2007 | -3.9°C | -8.0°C | -12.1°C | 1.6°C | -19.1°C | 97 mm | 97% | 0.4 m/s | 0.9 |
| 2006 | -2.5°C | -6.7°C | -11.0°C | 1.0°C | -18.5°C | 53 mm | 97% | 0.5 m/s | 1.1 |
| 2005 | -4.5°C | -8.9°C | -13.2°C | 1.1°C | -29.3°C | 71 mm | 99% | 0.4 m/s | 1.1 |
| 2004 | -0.7°C | -4.9°C | -9.1°C | 3.1°C | -18.8°C | 56 mm | 95% | 0.4 m/s | 1 |
| 2003 | -1.6°C | -5.8°C | -9.9°C | 4.6°C | -21.6°C | 59 mm | 95% | 0.5 m/s | 0.9 |
| 2002 | 0.4°C | -3.9°C | -8.1°C | 4.1°C | -14.0°C | 46 mm | 91% | 0.4 m/s | 1 |
| 2001 | -3.7°C | -8.6°C | -13.6°C | 0.1°C | -21.3°C | 56 mm | 98% | 0.4 m/s | 1 |
| 2000 | -3.3°C | -8.1°C | -12.9°C | 1.9°C | -22.9°C | 48 mm | 96% | 0.5 m/s | 1 |
| 1999 | -1.7°C | -5.8°C | -9.9°C | 1.0°C | -15.5°C | 64 mm | 95% | 0.4 m/s | 1 |
| 1998 | -4.3°C | -7.9°C | -11.5°C | 2.3°C | -28.4°C | 89 mm | 94% | 0.4 m/s | 0.8 |
| 1997 | -1.9°C | -6.2°C | -10.4°C | 2.0°C | -14.6°C | 32 mm | 93% | 0.4 m/s | 1.1 |
| 1996 | -4.7°C | -9.4°C | -14.1°C | 2.0°C | -27.6°C | 154 mm | 99% | 0.3 m/s | 1 |
| 1995 | -1.9°C | -6.0°C | -10.0°C | 2.4°C | -20.7°C | 66 mm | 93% | 0.4 m/s | 1 |
| 1994 | -2.3°C | -6.6°C | -11.0°C | 2.6°C | -18.7°C | 48 mm | 95% | 0.5 m/s | 1 |
| 1993 | -1.8°C | -5.7°C | -9.7°C | 3.0°C | -14.0°C | 43 mm | 95% | 0.4 m/s | 1 |
| 1992 | -4.4°C | -9.0°C | -13.6°C | 1.4°C | -25.9°C | 71 mm | 94% | 0.4 m/s | 1 |
| 1991 | -2.3°C | -7.1°C | -11.9°C | 0.3°C | -20.0°C | 57 mm | 99% | 0.4 m/s | 1.1 |
| 1990 | -8.2°C | -13.0°C | -17.8°C | 2.4°C | -37.3°C | 70 mm | 95% | 0.5 m/s | 1 |
| 1989 | -2.4°C | -6.7°C | -10.9°C | 3.9°C | -22.3°C | 70 mm | 96% | 0.4 m/s | 0.9 |
| 1988 | -3.0°C | -7.3°C | -11.6°C | 1.6°C | -24.6°C | 47 mm | 95% | 0.5 m/s | 1 |
| 1987 | -2.2°C | -6.2°C | -10.1°C | 7.4°C | -17.2°C | 53 mm | 91% | 0.4 m/s | 1 |
| 1986 | -2.9°C | -7.9°C | -13.0°C | 0.2°C | -19.3°C | 29 mm | 98% | 0.5 m/s | 1.1 |
| 1985 | -4.2°C | -9.3°C | -14.4°C | 0.0°C | -27.6°C | 20 mm | 100% | 0.4 m/s | 1.2 |
| 1984 | -5.0°C | -10.3°C | -15.5°C | 0.2°C | -22.7°C | 65 mm | 97% | 0.5 m/s | 1.2 |
| 1983 ❄️ | -8.9°C | -14.6°C | -20.4°C | 0.1°C | -39.7°C | 63 mm | 99% | 0.4 m/s | — |
| 1982 | -3.6°C | -7.8°C | -12.1°C | 2.0°C | -22.5°C | 60 mm | 96% | 0.4 m/s | — |
| 1981 | -3.1°C | -7.1°C | -11.0°C | 1.7°C | -18.7°C | 79 mm | 96% | 0.4 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around -3°C with lows near -11.8°C (mean -7.4°C), based on 45 years of NASA POWER data.
December averages 70 mm of rainfall in Missoula, a relatively wet time of year. The wettest on record was 176 mm in 2025.
The hottest December reached 9.7°C in 2021. The coldest dipped to -41°C in 2022.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 5.3°C. Daytime highs moved from -5°C to -0.6°C and overnight lows from -14.7°C to -8.4°C over the same span.
December is one of the cooler months of the year in Missoula and a relatively wet time of year, so plan for around -3°C daytime highs and -11.8°C at night.
Not quite — December is the 2nd coolest month in Missoula, averaging -7.4°C.
For December in Missoula, pack warm layers and a jacket for chilly mornings, with typical highs of -3°C and lows of -11.8°C. Bring an umbrella or light rain jacket too.
Relative humidity in December averages 96% — quite humid.
Average wind speed in December is 0.4 m/s. The windiest December on record averaged 0.5 m/s (1984).
The wettest December on record was 2025 with 176 mm. On average, December sees 70 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 Missoula 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.
