December is one of the cooler months of the year in Mission, with average highs near 4.3°C and lows around -0.8°C (mean 1.8°C). It is a relatively wet time of year, averaging 188 mm of rainfall and 91% relative humidity across the period.
December is one of the cooler months of the year in Mission. Across 45 years of records, the warmest December in Mission was 2023 — when the month averaged 5.3°C — while the coldest was 1983 at -3.2°C. Typical December days reach 4.3°C with nights near -0.8°C. The long-term trend is warming, about 0.4°C per decade.
December is a relatively wet time of year in Mission, averaging 188 mm of rainfall. The wettest December on record was 2025 with 369 mm, while the driest was 1985 at 41 mm.
Relative humidity in Mission during December averages 91%. The most humid December was 2025 at 95%, and the least humid was 2009 at 86%.
December receives about 0.7 kWh/m²/day of solar energy in Mission. The sunniest December was 2009 at 0.9 kWh/m²/day, and the cloudiest were 2006, 2012 and 2019 at 0.5.
Average wind speed in Mission during December is 0.9 m/s. The windiest December was 1996 at 1.1 m/s, while the calmest was 1989 at 0.7 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 1.0°C | 1.5°C | 2.0°C | 1.9°C | 2.5°C | +1.5°C |
| Avg High | 3.7°C | 4.1°C | 4.6°C | 4.4°C | 5.0°C | +1.3°C |
| Avg Low | -1.8°C | -1.0°C | -0.6°C | -0.5°C | 0.0°C | +1.8°C |
| Avg Rain | 149 mm | 206 mm | 166 mm | 190 mm | 249 mm | +101 mm |
December temperatures in Mission have risen by about 2.5°C between 1981–1985 and 2021–2025.
December has ranged from a record low of -23.3°C (1990) to a record high of 14.3°C (2014).
Rainfall in December is a relatively wet time of year, averaging 188 mm, with a wettest year of 369 mm.
Daytime highs and overnight lows have shifted differently — highs rose about 0.3°C per decade while lows rose 0.5°C per decade, narrowing the gap between day and night.
A quieter season to visit Mission
If your dates are flexible, the more temperate months of August and July tend to be the most comfortable for visiting Mission. That said, December — with days averaging 4.3°C and nights around -0.8°C (mean 1.8°C) and higher rainfall (188 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 🌧️ | 5.6°C | 3.7°C | 1.7°C | 12.2°C | -8.3°C | 369 mm | 95% | 0.9 m/s | — |
| 2024 | 5.9°C | 3.9°C | 1.8°C | 8.9°C | -2.1°C | 239 mm | 94% | 0.9 m/s | 0.7 |
| 2023 🔥 | 8.0°C | 5.3°C | 2.7°C | 12.6°C | -2.8°C | 220 mm | 93% | 0.8 m/s | 0.6 |
| 2022 | 2.4°C | -0.5°C | -3.5°C | 10.8°C | -15.6°C | 214 mm | 93% | 0.9 m/s | 0.8 |
| 2021 | 1.7°C | -0.9°C | -3.6°C | 11.5°C | -18.3°C | 204 mm | 93% | 1 m/s | 0.8 |
| 2020 | 6.3°C | 3.7°C | 1.2°C | 9.9°C | -5.7°C | 248 mm | 94% | 0.9 m/s | 0.7 |
| 2019 | 5.3°C | 3.3°C | 1.3°C | 8.7°C | -3.8°C | 195 mm | 93% | 0.9 m/s | 0.5 |
| 2018 | 5.7°C | 3.1°C | 0.4°C | 11.9°C | -5.6°C | 258 mm | 91% | 1 m/s | 0.7 |
| 2017 | 4.1°C | 1.2°C | -1.7°C | 10.4°C | -9.7°C | 183 mm | 88% | 0.9 m/s | 0.8 |
| 2016 | 1.4°C | -1.2°C | -3.8°C | 6.8°C | -13.3°C | 173 mm | 92% | 1 m/s | 0.7 |
| 2015 | 4.9°C | 2.6°C | 0.3°C | 12.4°C | -10.8°C | 272 mm | 93% | 1 m/s | 0.6 |
| 2014 | 6.4°C | 3.6°C | 0.9°C | 14.3°C | -9.0°C | 189 mm | 91% | 0.8 m/s | 0.8 |
| 2013 | 2.8°C | 0.5°C | -1.8°C | 9.4°C | -13.6°C | 104 mm | 87% | 0.9 m/s | 0.7 |
| 2012 | 4.0°C | 2.0°C | 0.1°C | 8.2°C | -5.4°C | 199 mm | 94% | 0.9 m/s | 0.5 |
| 2011 | 4.6°C | 2.0°C | -0.5°C | 9.1°C | -5.9°C | 109 mm | 89% | 0.8 m/s | 0.8 |
| 2010 | 4.5°C | 2.0°C | -0.4°C | 10.0°C | -10.4°C | 214 mm | 91% | 0.9 m/s | 0.6 |
| 2009 | 3.1°C | 0.1°C | -2.9°C | 10.5°C | -11.4°C | 85 mm | 86% | 0.9 m/s | 0.9 |
| 2008 | 1.6°C | -1.1°C | -3.8°C | 12.1°C | -17.5°C | 153 mm | 90% | 1 m/s | 0.7 |
| 2007 | 3.8°C | 1.8°C | -0.2°C | 11.6°C | -5.3°C | 244 mm | 93% | 1 m/s | 0.6 |
| 2006 | 5.3°C | 2.8°C | 0.3°C | 9.7°C | -7.0°C | 179 mm | 91% | 1 m/s | 0.5 |
| 2005 | 5.7°C | 3.1°C | 0.5°C | 13.8°C | -6.2°C | 152 mm | 88% | 0.8 m/s | 0.7 |
| 2004 | 6.1°C | 3.7°C | 1.3°C | 11.8°C | -1.8°C | 210 mm | 93% | 0.8 m/s | 0.7 |
| 2003 | 4.8°C | 2.4°C | -0.1°C | 10.1°C | -7.9°C | 137 mm | 93% | 0.9 m/s | 0.6 |
| 2002 | 6.8°C | 4.0°C | 1.2°C | 13.4°C | -3.7°C | 167 mm | 91% | 1 m/s | 0.6 |
| 2001 | 4.2°C | 1.8°C | -0.6°C | 6.9°C | -5.7°C | 207 mm | 93% | 1 m/s | 0.7 |
| 2000 | 4.3°C | 1.5°C | -1.3°C | 9.7°C | -8.4°C | 122 mm | 88% | 0.9 m/s | 0.7 |
| 1999 | 6.1°C | 3.8°C | 1.6°C | 10.7°C | -1.7°C | 238 mm | 91% | 0.9 m/s | 0.6 |
| 1998 | 3.6°C | 1.5°C | -0.6°C | 12.0°C | -16.3°C | 302 mm | 92% | 1 m/s | 0.6 |
| 1997 | 6.0°C | 3.4°C | 0.8°C | 10.1°C | -2.3°C | 172 mm | 92% | 0.9 m/s | 0.7 |
| 1996 | 1.7°C | -1.0°C | -3.6°C | 7.1°C | -15.5°C | 245 mm | 93% | 1.1 m/s | 0.6 |
| 1995 | 4.8°C | 2.2°C | -0.3°C | 9.2°C | -12.2°C | 202 mm | 90% | 0.9 m/s | 0.7 |
| 1994 | 4.1°C | 1.5°C | -1.0°C | 10.4°C | -13.0°C | 216 mm | 91% | 0.9 m/s | 0.7 |
| 1993 | 5.7°C | 3.0°C | 0.3°C | 12.3°C | -4.5°C | 170 mm | 87% | 0.9 m/s | 0.7 |
| 1992 | 2.0°C | -0.5°C | -3.1°C | 6.3°C | -13.4°C | 128 mm | 90% | 1 m/s | 0.7 |
| 1991 | 6.0°C | 3.6°C | 1.3°C | 9.8°C | -3.8°C | 141 mm | 92% | 0.9 m/s | 0.6 |
| 1990 | 0.9°C | -2.1°C | -5.1°C | 7.0°C | -23.3°C | 242 mm | 91% | 1 m/s | 0.7 |
| 1989 | 6.8°C | 4.3°C | 1.8°C | 12.9°C | -3.3°C | 140 mm | 91% | 0.7 m/s | 0.6 |
| 1988 | 4.9°C | 2.5°C | 0.1°C | 10.7°C | -8.1°C | 154 mm | 90% | 0.9 m/s | 0.7 |
| 1987 | 3.5°C | 0.8°C | -1.9°C | 10.5°C | -10.1°C | 179 mm | 89% | 1 m/s | 0.7 |
| 1986 | 5.3°C | 2.3°C | -0.7°C | 8.6°C | -5.8°C | 131 mm | 91% | 0.9 m/s | 0.7 |
| 1985 | 4.1°C | 1.4°C | -1.4°C | 7.8°C | -16.4°C | 41 mm | 86% | 0.9 m/s | 0.7 |
| 1984 | 0.5°C | -2.7°C | -6.0°C | 5.5°C | -18.0°C | 176 mm | 91% | 0.9 m/s | 0.7 |
| 1983 ❄️ | -0.2°C | -3.2°C | -6.1°C | 6.1°C | -19.7°C | 99 mm | 87% | 0.9 m/s | — |
| 1982 | 4.2°C | 1.6°C | -1.1°C | 10.2°C | -6.3°C | 200 mm | 90% | 0.9 m/s | — |
| 1981 | 4.0°C | 1.7°C | -0.6°C | 10.3°C | -8.2°C | 217 mm | 93% | 0.9 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around 4.3°C with lows near -0.8°C (mean 1.8°C), based on 45 years of NASA POWER data.
December averages 188 mm of rainfall in Mission, a relatively wet time of year. The wettest on record was 369 mm in 2025.
The hottest December reached 14.3°C in 2014. The coldest dipped to -23.3°C in 1990.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 2.5°C. Daytime highs moved from 2.5°C to 4.7°C and overnight lows from -3°C to -0.2°C over the same span.
December is one of the cooler months of the year in Mission and a relatively wet time of year, so plan for around 4.3°C daytime highs and -0.8°C at night.
Yes — December is the coldest month of the year in Mission, averaging 1.8°C.
For December in Mission, pack warm layers and a jacket for chilly mornings, with typical highs of 4.3°C and lows of -0.8°C. Bring an umbrella or light rain jacket too.
Relative humidity in December averages 91% — quite humid.
Average wind speed in December is 0.9 m/s. The windiest December on record averaged 1.1 m/s (1996).
The wettest December on record was 2025 with 369 mm. On average, December sees 188 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 Mission 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.
