December is one of the cooler months of the year in Mount Prospect, with average highs near 0.8°C and lows around -7.1°C (mean -3.1°C). It is one of the drier months, averaging 56 mm of rainfall and 87% relative humidity across the period.
December is one of the cooler months of the year in Mount Prospect. Across 45 years of records, the warmest December in Mount Prospect was 2015 — when the month averaged 2.5°C — while the coldest was 1983 at -11.6°C. Typical December days reach 0.8°C with nights near -7.1°C. The long-term trend is warming, about 0.8°C per decade.
December is one of the drier months in Mount Prospect, averaging 56 mm of rainfall. The wettest December on record was 1982 with 148 mm, while the driest was 2017 at 11 mm.
Relative humidity in Mount Prospect during December averages 87%. The most humid December was 1983 at 95%, and the least humid was 2017 at 80%.
December receives about 1.2 kWh/m²/day of solar energy in Mount Prospect. The sunniest Decembers were 1995, 1998 and 2001 at 1.5 kWh/m²/day, and the cloudiest were 1987 and 1992 at 1.
Average wind speed in Mount Prospect during December is 3.8 m/s. The windiest December was 2008 at 4.6 m/s, while the calmest was 1994 at 2.9 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | -5.4°C | -2.8°C | -3.7°C | -2.1°C | -1.4°C | +4°C |
| Avg High | -1.2°C | 1.0°C | 0.3°C | 1.6°C | 2.6°C | +3.8°C |
| Avg Low | -9.6°C | -6.6°C | -7.7°C | -5.8°C | -5.5°C | +4.1°C |
| Avg Rain | 64 mm | 45 mm | 61 mm | 53 mm | 57 mm | -7 mm |
December temperatures in Mount Prospect have risen by about 4.2°C between 1981–1985 and 2021–2025.
December has ranged from a record low of -35.4°C (1983) to a record high of 19.9°C (2012).
Rainfall in December is one of the drier months, averaging 56 mm, with a wettest year of 148 mm.
A quieter season to visit Mount Prospect
If your dates are flexible, the more temperate months of August and July tend to be the most comfortable for visiting Mount Prospect. That said, December — with days averaging 0.8°C and nights around -7.1°C (mean -3.1°C) and moderate rainfall (56 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 | -0.4°C | -5.4°C | -10.4°C | 12.2°C | -23.9°C | 54 mm | 87% | 3.9 m/s | — |
| 2024 | 2.5°C | -1.5°C | -5.5°C | 10.9°C | -16.0°C | 38 mm | 83% | 3.7 m/s | 1.1 |
| 2023 | 5.6°C | 2.0°C | -1.5°C | 13.6°C | -6.6°C | 72 mm | 86% | 3.2 m/s | 1.2 |
| 2022 | 0.4°C | -3.6°C | -7.6°C | 11.3°C | -23.0°C | 60 mm | 85% | 4.2 m/s | 1.1 |
| 2021 | 5.5°C | 1.2°C | -3.2°C | 17.4°C | -10.5°C | 63 mm | 82% | 3.8 m/s | 1.3 |
| 2020 | 2.3°C | -1.4°C | -5.1°C | 11.1°C | -12.1°C | 54 mm | 85% | 3.5 m/s | 1.3 |
| 2019 | 3.9°C | 0.0°C | -3.9°C | 13.0°C | -13.5°C | 41 mm | 89% | 3.8 m/s | 1.4 |
| 2018 | 2.8°C | -0.7°C | -4.1°C | 8.8°C | -11.8°C | 74 mm | 89% | 3.2 m/s | 1.3 |
| 2017 | -0.4°C | -4.1°C | -7.7°C | 15.3°C | -22.1°C | 11 mm | 80% | 3.9 m/s | 1.4 |
| 2016 | -1.5°C | -5.4°C | -9.4°C | 7.9°C | -27.4°C | 37 mm | 88% | 4 m/s | 1.2 |
| 2015 🔥 | 5.8°C | 2.5°C | -0.8°C | 15.5°C | -10.3°C | 132 mm | 90% | 4 m/s | 1.2 |
| 2014 | 1.7°C | -1.3°C | -4.4°C | 7.8°C | -17.3°C | 21 mm | 86% | 3.3 m/s | 1.2 |
| 2013 | -2.3°C | -6.5°C | -10.6°C | 11.8°C | -20.5°C | 38 mm | 88% | 3.6 m/s | 1.2 |
| 2012 | 4.6°C | 0.6°C | -3.4°C | 19.9°C | -12.8°C | 58 mm | 86% | 3.7 m/s | 1.1 |
| 2011 | 3.9°C | 0.2°C | -3.4°C | 10.7°C | -13.3°C | 62 mm | 86% | 3.5 m/s | 1.4 |
| 2010 | -2.2°C | -6.3°C | -10.4°C | 10.6°C | -20.9°C | 54 mm | 91% | 3.7 m/s | 1.2 |
| 2009 | -1.0°C | -4.7°C | -8.4°C | 11.3°C | -19.3°C | 85 mm | 92% | 3.8 m/s | 1.1 |
| 2008 | -2.1°C | -7.1°C | -12.1°C | 15.2°C | -24.4°C | 131 mm | 90% | 4.6 m/s | 1.2 |
| 2007 | -0.3°C | -4.2°C | -8.0°C | 5.8°C | -17.0°C | 91 mm | 92% | 3.5 m/s | 1.1 |
| 2006 | 3.4°C | -1.1°C | -5.6°C | 13.0°C | -23.5°C | 76 mm | 91% | 3.8 m/s | 1.2 |
| 2005 | -1.7°C | -5.2°C | -8.6°C | 5.9°C | -18.8°C | 30 mm | 89% | 3.5 m/s | 1.1 |
| 2004 | 1.5°C | -2.4°C | -6.2°C | 11.5°C | -20.0°C | 30 mm | 84% | 4.3 m/s | 1.3 |
| 2003 | 2.6°C | -1.1°C | -4.8°C | 10.1°C | -13.3°C | 55 mm | 85% | 3.9 m/s | 1.4 |
| 2002 | 2.3°C | -1.4°C | -5.1°C | 11.0°C | -12.3°C | 28 mm | 82% | 3.9 m/s | 1.3 |
| 2001 | 4.0°C | 0.1°C | -3.8°C | 19.5°C | -14.7°C | 30 mm | 86% | 3.8 m/s | 1.5 |
| 2000 | -5.4°C | -9.7°C | -14.1°C | 3.1°C | -23.6°C | 52 mm | 92% | 3.5 m/s | 1.2 |
| 1999 | 2.3°C | -2.1°C | -6.5°C | 13.8°C | -17.8°C | 61 mm | 83% | 3.6 m/s | 1.2 |
| 1998 | 4.4°C | -0.1°C | -4.5°C | 19.0°C | -18.2°C | 31 mm | 82% | 3.6 m/s | 1.5 |
| 1997 | 1.0°C | -2.0°C | -5.1°C | 5.8°C | -15.0°C | 39 mm | 89% | 3.3 m/s | 1.3 |
| 1996 | -0.3°C | -3.7°C | -7.1°C | 4.9°C | -18.0°C | 45 mm | 88% | 3.6 m/s | 1.2 |
| 1995 | -1.1°C | -4.9°C | -8.7°C | 7.5°C | -18.2°C | 18 mm | 85% | 3.9 m/s | 1.5 |
| 1994 | 2.2°C | -1.5°C | -5.3°C | 13.1°C | -18.6°C | 42 mm | 92% | 2.9 m/s | 1.2 |
| 1993 | -0.1°C | -3.2°C | -6.2°C | 7.8°C | -19.3°C | 32 mm | 87% | 3.7 m/s | 1.2 |
| 1992 | 0.0°C | -3.9°C | -7.7°C | 6.2°C | -20.1°C | 75 mm | 89% | 3.8 m/s | 1 |
| 1991 | 1.6°C | -2.5°C | -6.6°C | 14.8°C | -17.1°C | 41 mm | 89% | 3.8 m/s | 1.2 |
| 1990 | -0.3°C | -4.5°C | -8.8°C | 8.2°C | -24.2°C | 61 mm | 88% | 4.1 m/s | 1.3 |
| 1989 | -5.2°C | -9.4°C | -13.6°C | 6.5°C | -26.9°C | 14 mm | 81% | 3.8 m/s | 1.2 |
| 1988 | 0.3°C | -4.2°C | -8.6°C | 9.3°C | -21.2°C | 49 mm | 84% | 4.2 m/s | 1.4 |
| 1987 | 0.4°C | -3.5°C | -7.5°C | 6.3°C | -18.6°C | 113 mm | 91% | 4 m/s | 1 |
| 1986 | 0.5°C | -2.8°C | -6.1°C | 5.5°C | -18.2°C | 25 mm | 90% | 3.4 m/s | 1.2 |
| 1985 | -5.9°C | -11.2°C | -16.5°C | 3.1°C | -27.5°C | 42 mm | 93% | 4.3 m/s | 1.3 |
| 1984 | 2.7°C | -1.5°C | -5.7°C | 15.5°C | -18.3°C | 89 mm | 87% | 4.3 m/s | 1.1 |
| 1983 ❄️ | -7.2°C | -11.6°C | -16.1°C | 4.1°C | -35.4°C | 72 mm | 95% | 3.9 m/s | — |
| 1982 🌧️ | 4.5°C | 0.3°C | -3.8°C | 18.2°C | -14.0°C | 148 mm | 89% | 4.2 m/s | — |
| 1981 | -0.8°C | -4.5°C | -8.3°C | 5.7°C | -16.5°C | 23 mm | 88% | 3.6 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around 0.8°C with lows near -7.1°C (mean -3.1°C), based on 45 years of NASA POWER data.
December averages 56 mm of rainfall in Mount Prospect, one of the drier months. The wettest on record was 148 mm in 1982.
The hottest December reached 19.9°C in 2012. The coldest dipped to -35.4°C in 1983.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 4.2°C. Daytime highs moved from -1.3°C to 2.7°C and overnight lows from -10.1°C to -5.6°C over the same span.
December is one of the cooler months of the year in Mount Prospect and one of the drier months, so plan for around 0.8°C daytime highs and -7.1°C at night.
Not quite — December is the 3rd coolest month in Mount Prospect, averaging -3.1°C.
For December in Mount Prospect, pack warm layers and a jacket for chilly mornings, with typical highs of 0.8°C and lows of -7.1°C. Bring an umbrella or light rain jacket too.
Relative humidity in December averages 87% — quite humid.
Average wind speed in December is 3.8 m/s. The windiest December on record averaged 4.6 m/s (2008).
The wettest December on record was 1982 with 148 mm. On average, December sees 56 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 Mount Prospect 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.
