December is one of the cooler months of the year in Mchenry, with average highs near 0.2°C and lows around -7.6°C (mean -3.7°C). It is one of the drier months, averaging 52 mm of rainfall and 88% relative humidity across the period.
December is one of the cooler months of the year in Mchenry. Across 45 years of records, the warmest December in Mchenry was 2015 — when the month averaged 1.9°C — while the coldest was 1985 at -12.7°C. Typical December days reach 0.2°C with nights near -7.6°C. The long-term trend is warming, about 0.8°C per decade.
December is one of the drier months in Mchenry, averaging 52 mm of rainfall. The wettest December on record was 2015 with 123 mm, while the driest was 1989 at 11 mm.
Relative humidity in Mchenry during December averages 88%. The most humid December was 1985 at 96%, and the least humid was 1989 at 79%.
December receives about 1.4 kWh/m²/day of solar energy in Mchenry. The sunniest Decembers were 1985 and 1998 at 1.7 kWh/m²/day, and the cloudiest was 1984 at 1.1.
Average wind speed in Mchenry during December is 4 m/s. The windiest December was 2008 at 4.7 m/s, while the calmest was 1994 at 3.2 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | -5.9°C | -3.2°C | -4.2°C | -2.7°C | -2.0°C | +3.9°C |
| Avg High | -1.7°C | 0.6°C | -0.2°C | 1.0°C | 1.9°C | +3.6°C |
| Avg Low | -10.1°C | -7.0°C | -8.1°C | -6.4°C | -6.0°C | +4.1°C |
| Avg Rain | 56 mm | 39 mm | 60 mm | 52 mm | 51 mm | -5 mm |
December temperatures in Mchenry have risen by about 4.3°C between 1981–1985 and 2021–2025.
December has ranged from a record low of -35.1°C (1983) to a record high of 19°C (2001).
Rainfall in December is one of the drier months, averaging 52 mm, with a wettest year of 123 mm.
Daytime highs and overnight lows have shifted differently — highs rose about 0.7°C per decade while lows rose 0.9°C per decade, narrowing the gap between day and night.
A quieter season to visit Mchenry
If your dates are flexible, the more temperate months of August and July tend to be the most comfortable for visiting Mchenry. That said, December — with days averaging 0.2°C and nights around -7.6°C (mean -3.7°C) and moderate rainfall (52 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 | -1.3°C | -6.1°C | -11.0°C | 9.5°C | -24.5°C | 51 mm | 88% | 4.1 m/s | — |
| 2024 | 2.1°C | -1.9°C | -5.9°C | 10.6°C | -16.9°C | 30 mm | 83% | 3.9 m/s | 1.4 |
| 2023 | 5.0°C | 1.7°C | -1.6°C | 12.9°C | -7.0°C | 62 mm | 86% | 3.4 m/s | 1.2 |
| 2022 | -0.5°C | -4.4°C | -8.2°C | 10.0°C | -23.5°C | 60 mm | 88% | 4.3 m/s | 1.2 |
| 2021 | 4.6°C | 0.4°C | -3.7°C | 17.4°C | -11.0°C | 56 mm | 81% | 4 m/s | 1.4 |
| 2020 | 1.7°C | -1.8°C | -5.4°C | 10.0°C | -11.7°C | 48 mm | 86% | 3.7 m/s | 1.5 |
| 2019 | 3.3°C | -0.4°C | -4.2°C | 12.1°C | -14.9°C | 43 mm | 89% | 3.9 m/s | 1.5 |
| 2018 | 1.9°C | -1.4°C | -4.8°C | 8.0°C | -12.8°C | 65 mm | 90% | 3.3 m/s | 1.4 |
| 2017 | -1.0°C | -4.6°C | -8.2°C | 14.6°C | -22.5°C | 12 mm | 81% | 4.1 m/s | 1.5 |
| 2016 | -2.2°C | -6.0°C | -9.9°C | 5.9°C | -28.5°C | 48 mm | 89% | 4.3 m/s | 1.3 |
| 2015 🔥 🌧️ | 5.1°C | 1.9°C | -1.4°C | 15.1°C | -11.2°C | 123 mm | 90% | 4.1 m/s | 1.2 |
| 2014 | 1.3°C | -1.8°C | -4.9°C | 7.2°C | -18.5°C | 21 mm | 86% | 3.4 m/s | 1.3 |
| 2013 | -3.0°C | -7.3°C | -11.5°C | 10.2°C | -21.8°C | 42 mm | 89% | 3.8 m/s | 1.5 |
| 2012 | 3.4°C | -0.5°C | -4.4°C | 18.8°C | -15.2°C | 69 mm | 88% | 3.7 m/s | 1.2 |
| 2011 | 3.4°C | -0.2°C | -3.9°C | 9.3°C | -13.3°C | 56 mm | 85% | 3.7 m/s | 1.4 |
| 2010 | -2.6°C | -6.5°C | -10.4°C | 9.2°C | -20.4°C | 43 mm | 92% | 3.9 m/s | 1.4 |
| 2009 | -1.3°C | -5.3°C | -9.3°C | 10.7°C | -22.4°C | 84 mm | 92% | 3.9 m/s | 1.4 |
| 2008 | -2.9°C | -7.8°C | -12.8°C | 10.5°C | -24.3°C | 118 mm | 90% | 4.7 m/s | 1.4 |
| 2007 | -1.3°C | -5.3°C | -9.3°C | 4.9°C | -19.9°C | 101 mm | 94% | 3.6 m/s | 1.2 |
| 2006 | 3.1°C | -1.2°C | -5.4°C | 12.2°C | -21.9°C | 69 mm | 91% | 4.1 m/s | 1.3 |
| 2005 | -2.4°C | -5.7°C | -9.0°C | 4.5°C | -18.1°C | 29 mm | 90% | 3.7 m/s | 1.3 |
| 2004 | 1.0°C | -2.8°C | -6.6°C | 10.7°C | -20.5°C | 28 mm | 83% | 4.5 m/s | 1.6 |
| 2003 | 2.2°C | -1.5°C | -5.1°C | 9.6°C | -14.4°C | 62 mm | 84% | 4 m/s | 1.5 |
| 2002 | 1.7°C | -1.9°C | -5.5°C | 9.8°C | -12.4°C | 22 mm | 83% | 4.1 m/s | 1.6 |
| 2001 | 3.6°C | -0.1°C | -3.8°C | 19.0°C | -15.2°C | 29 mm | 85% | 4 m/s | 1.6 |
| 2000 | -5.5°C | -10.0°C | -14.5°C | 2.6°C | -23.8°C | 58 mm | 92% | 3.7 m/s | 1.5 |
| 1999 | 1.7°C | -2.5°C | -6.8°C | 13.0°C | -19.0°C | 47 mm | 84% | 3.8 m/s | 1.4 |
| 1998 | 3.8°C | -0.5°C | -4.9°C | 18.1°C | -19.3°C | 28 mm | 82% | 3.9 m/s | 1.7 |
| 1997 | 1.1°C | -1.9°C | -5.0°C | 5.7°C | -13.7°C | 31 mm | 88% | 3.6 m/s | 1.5 |
| 1996 | -0.9°C | -4.3°C | -7.7°C | 4.6°C | -19.2°C | 45 mm | 88% | 3.8 m/s | 1.3 |
| 1995 | -1.7°C | -5.4°C | -9.2°C | 6.4°C | -19.2°C | 19 mm | 85% | 4.1 m/s | 1.6 |
| 1994 | 2.2°C | -1.4°C | -4.9°C | 11.5°C | -15.7°C | 28 mm | 90% | 3.2 m/s | 1.4 |
| 1993 | -0.4°C | -3.5°C | -6.6°C | 7.1°C | -20.2°C | 26 mm | 86% | 3.8 m/s | 1.4 |
| 1992 | -0.5°C | -4.5°C | -8.4°C | 4.8°C | -22.0°C | 72 mm | 90% | 4 m/s | 1.4 |
| 1991 | 1.2°C | -3.1°C | -7.3°C | 13.9°C | -17.6°C | 42 mm | 89% | 3.9 m/s | 1.4 |
| 1990 | -0.9°C | -5.2°C | -9.6°C | 7.2°C | -26.9°C | 57 mm | 88% | 4.4 m/s | 1.5 |
| 1989 | -5.5°C | -9.7°C | -13.8°C | 6.3°C | -26.9°C | 11 mm | 79% | 4.1 m/s | 1.6 |
| 1988 | -0.3°C | -4.7°C | -9.1°C | 8.2°C | -22.0°C | 43 mm | 84% | 4.5 m/s | 1.5 |
| 1987 | 0.2°C | -3.7°C | -7.5°C | 5.8°C | -18.7°C | 104 mm | 90% | 4.2 m/s | 1.3 |
| 1986 | 0.1°C | -3.3°C | -6.7°C | 4.8°C | -19.4°C | 21 mm | 90% | 3.6 m/s | 1.3 |
| 1985 ❄️ | -7.2°C | -12.7°C | -18.2°C | 1.6°C | -29.1°C | 48 mm | 96% | 4.3 m/s | 1.7 |
| 1984 | 1.8°C | -2.2°C | -6.3°C | 15.3°C | -20.2°C | 84 mm | 87% | 4.5 m/s | 1.1 |
| 1983 | -7.5°C | -11.9°C | -16.3°C | 3.3°C | -35.1°C | 64 mm | 95% | 4.1 m/s | — |
| 1982 | 3.7°C | -0.4°C | -4.5°C | 17.3°C | -14.1°C | 110 mm | 88% | 4.3 m/s | — |
| 1981 | -1.0°C | -4.7°C | -8.3°C | 5.5°C | -16.2°C | 20 mm | 88% | 3.8 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 -7.6°C (mean -3.7°C), based on 45 years of NASA POWER data.
December averages 52 mm of rainfall in Mchenry, one of the drier months. The wettest on record was 123 mm in 2015.
The hottest December reached 19°C in 2001. The coldest dipped to -35.1°C in 1983.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 4.3°C. Daytime highs moved from -2°C to 2°C and overnight lows from -10.7°C to -6.1°C over the same span.
December is one of the cooler months of the year in Mchenry and one of the drier months, so plan for around 0.2°C daytime highs and -7.6°C at night.
Not quite — December is the 3rd coolest month in Mchenry, averaging -3.7°C.
For December in Mchenry, pack warm layers and a jacket for chilly mornings, with typical highs of 0.2°C and lows of -7.6°C. Bring an umbrella or light rain jacket too.
Relative humidity in December averages 88% — quite humid.
Average wind speed in December is 4 m/s. The windiest December on record averaged 4.7 m/s (2008).
The wettest December on record was 2015 with 123 mm. On average, December sees 52 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 Mchenry 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.
