December is one of the cooler months of the year in Normal, with average highs near 2.5°C and lows around -5.9°C (mean -1.7°C). It is one of the drier months, averaging 63 mm of rainfall and 85% relative humidity across the period.
December is one of the cooler months of the year in Normal. Across 45 years of records, the warmest December in Normal was 2015 — when the month averaged 3.9°C — while the coldest were 1983 and 1985 at -10.4°C. Typical December days reach 2.5°C with nights near -5.9°C. The long-term trend is warming, about 1°C per decade.
December is one of the drier months in Normal, averaging 63 mm of rainfall. The wettest December on record was 1982 with 174 mm, while the driest was 2017 at 14 mm.
Relative humidity in Normal during December averages 85%. The most humid December was 1985 at 92%, and the least humid was 2017 at 75%.
December receives about 1.5 kWh/m²/day of solar energy in Normal. The sunniest Decembers were 2004, 2017 and 2020, among others at 1.8 kWh/m²/day, and the cloudiest were 2014, 2015 and 2022, among others at 1.3.
Average wind speed in Normal during December is 3.7 m/s. The windiest December was 2008 at 4.8 m/s, while the calmest was 1994 at 3 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | -4.1°C | -1.3°C | -2.3°C | -0.6°C | 0.3°C | +4.4°C |
| Avg High | 0.3°C | 2.7°C | 1.9°C | 3.6°C | 4.8°C | +4.5°C |
| Avg Low | -8.4°C | -5.4°C | -6.5°C | -4.7°C | -4.2°C | +4.2°C |
| Avg Rain | 77 mm | 53 mm | 62 mm | 61 mm | 61 mm | -16 mm |
December temperatures in Normal have risen by about 4.9°C between 1981–1985 and 2021–2025.
December has ranged from a record low of -32.1°C (1983) to a record high of 21.2°C (1998).
Rainfall in December is one of the drier months, averaging 63 mm, with a wettest year of 174 mm.
A quieter season to visit Normal
If your dates are flexible, the more temperate months of August and June tend to be the most comfortable for visiting Normal. That said, December — with days averaging 2.5°C and nights around -5.9°C (mean -1.7°C) and moderate rainfall (63 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 | 2.2°C | -3.0°C | -8.2°C | 20.6°C | -23.1°C | 55 mm | 83% | 3.8 m/s | — |
| 2024 | 3.9°C | -0.2°C | -4.2°C | 11.6°C | -13.2°C | 73 mm | 82% | 3.8 m/s | 1.5 |
| 2023 | 7.0°C | 3.0°C | -1.1°C | 15.6°C | -6.9°C | 78 mm | 82% | 3.3 m/s | 1.4 |
| 2022 | 3.0°C | -1.3°C | -5.6°C | 13.7°C | -20.7°C | 57 mm | 80% | 4.1 m/s | 1.3 |
| 2021 | 8.5°C | 3.5°C | -1.6°C | 18.1°C | -8.6°C | 63 mm | 82% | 3.9 m/s | 1.6 |
| 2020 | 4.2°C | -0.1°C | -4.5°C | 14.6°C | -13.3°C | 39 mm | 81% | 3.3 m/s | 1.8 |
| 2019 | 5.7°C | 1.3°C | -3.2°C | 17.5°C | -10.1°C | 37 mm | 87% | 3.8 m/s | 1.7 |
| 2018 | 5.0°C | 0.7°C | -3.6°C | 12.5°C | -10.2°C | 91 mm | 87% | 3.4 m/s | 1.6 |
| 2017 | 1.9°C | -2.3°C | -6.4°C | 17.4°C | -22.2°C | 14 mm | 75% | 3.9 m/s | 1.8 |
| 2016 | 1.0°C | -3.0°C | -7.0°C | 13.0°C | -21.4°C | 29 mm | 81% | 3.9 m/s | 1.6 |
| 2015 🔥 | 7.9°C | 3.9°C | -0.1°C | 18.8°C | -9.2°C | 165 mm | 88% | 4.3 m/s | 1.3 |
| 2014 | 3.3°C | -0.2°C | -3.6°C | 11.0°C | -14.4°C | 30 mm | 85% | 3.2 m/s | 1.3 |
| 2013 | 0.2°C | -4.1°C | -8.5°C | 16.0°C | -18.7°C | 41 mm | 84% | 3.7 m/s | 1.4 |
| 2012 | 6.4°C | 2.1°C | -2.1°C | 20.6°C | -10.1°C | 54 mm | 84% | 3.8 m/s | 1.4 |
| 2011 | 5.6°C | 1.4°C | -2.8°C | 13.8°C | -9.5°C | 80 mm | 85% | 3.5 m/s | 1.5 |
| 2010 | -1.4°C | -5.4°C | -9.5°C | 13.9°C | -18.4°C | 75 mm | 90% | 3.6 m/s | 1.6 |
| 2009 | 0.6°C | -3.0°C | -6.6°C | 11.9°C | -17.3°C | 97 mm | 89% | 4.1 m/s | 1.3 |
| 2008 | 0.1°C | -4.8°C | -9.8°C | 18.4°C | -21.8°C | 104 mm | 85% | 4.8 m/s | 1.6 |
| 2007 | 1.8°C | -1.9°C | -5.6°C | 13.2°C | -14.1°C | 97 mm | 88% | 3.5 m/s | 1.3 |
| 2006 | 5.0°C | 0.1°C | -4.8°C | 14.2°C | -25.0°C | 78 mm | 89% | 3.8 m/s | 1.7 |
| 2005 | 0.0°C | -3.9°C | -7.8°C | 9.5°C | -17.4°C | 33 mm | 87% | 3.5 m/s | 1.5 |
| 2004 | 3.4°C | -0.9°C | -5.2°C | 15.8°C | -17.3°C | 36 mm | 83% | 4.1 m/s | 1.8 |
| 2003 | 3.8°C | -0.3°C | -4.3°C | 10.7°C | -12.5°C | 50 mm | 83% | 3.9 m/s | 1.7 |
| 2002 | 3.9°C | -0.1°C | -4.1°C | 13.6°C | -11.6°C | 42 mm | 79% | 3.9 m/s | 1.7 |
| 2001 | 5.2°C | 0.9°C | -3.3°C | 19.5°C | -12.7°C | 44 mm | 84% | 3.7 m/s | 1.8 |
| 2000 | -4.7°C | -9.1°C | -13.5°C | 5.0°C | -24.3°C | 42 mm | 91% | 3.4 m/s | 1.8 |
| 1999 | 4.4°C | -0.4°C | -5.1°C | 17.7°C | -14.3°C | 61 mm | 79% | 3.7 m/s | 1.4 |
| 1998 | 5.9°C | 1.1°C | -3.8°C | 21.2°C | -16.3°C | 34 mm | 78% | 3.3 m/s | 1.7 |
| 1997 | 2.1°C | -1.3°C | -4.7°C | 8.0°C | -15.0°C | 43 mm | 88% | 3.2 m/s | 1.7 |
| 1996 | 2.2°C | -1.6°C | -5.4°C | 12.2°C | -14.6°C | 27 mm | 83% | 3.7 m/s | 1.3 |
| 1995 | 0.9°C | -3.5°C | -8.0°C | 14.7°C | -18.0°C | 23 mm | 81% | 3.7 m/s | 1.6 |
| 1994 | 4.5°C | 0.6°C | -3.3°C | 14.2°C | -13.4°C | 58 mm | 89% | 3 m/s | 1.4 |
| 1993 | 1.3°C | -1.9°C | -5.2°C | 9.8°C | -17.8°C | 38 mm | 90% | 3.8 m/s | 1.3 |
| 1992 | 1.3°C | -2.4°C | -6.1°C | 7.5°C | -17.0°C | 75 mm | 87% | 3.6 m/s | 1.3 |
| 1991 | 3.2°C | -0.8°C | -4.9°C | 17.5°C | -15.6°C | 50 mm | 87% | 3.8 m/s | 1.7 |
| 1990 | 1.3°C | -3.3°C | -7.9°C | 12.6°C | -24.1°C | 121 mm | 87% | 4 m/s | 1.5 |
| 1989 | -4.1°C | -8.5°C | -12.8°C | 8.0°C | -28.7°C | 20 mm | 79% | 3.6 m/s | 1.7 |
| 1988 | 2.6°C | -2.2°C | -7.0°C | 13.5°C | -15.3°C | 63 mm | 79% | 4.2 m/s | 1.7 |
| 1987 | 2.2°C | -1.8°C | -5.9°C | 11.5°C | -17.7°C | 119 mm | 89% | 4.1 m/s | 1.3 |
| 1986 | 2.0°C | -1.4°C | -4.8°C | 9.4°C | -15.3°C | 34 mm | 89% | 3.1 m/s | 1.4 |
| 1985 | -4.5°C | -10.4°C | -16.2°C | 5.7°C | -29.4°C | 57 mm | 92% | 4 m/s | 1.7 |
| 1984 | 5.0°C | 0.4°C | -4.2°C | 17.3°C | -16.1°C | 99 mm | 86% | 4.2 m/s | 1.3 |
| 1983 ❄️ | -6.3°C | -10.4°C | -14.5°C | 3.4°C | -32.1°C | 87 mm | 92% | 3.7 m/s | — |
| 1982 🌧️ | 6.1°C | 1.8°C | -2.5°C | 19.5°C | -15.5°C | 174 mm | 88% | 4.2 m/s | — |
| 1981 | 0.0°C | -4.0°C | -8.1°C | 7.1°C | -16.9°C | 39 mm | 87% | 3.5 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around 2.5°C with lows near -5.9°C (mean -1.7°C), based on 45 years of NASA POWER data.
December averages 63 mm of rainfall in Normal, one of the drier months. The wettest on record was 174 mm in 1982.
The hottest December reached 21.2°C in 1998. The coldest dipped to -32.1°C in 1983.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 4.9°C. Daytime highs moved from 0.1°C to 4.9°C and overnight lows from -9.1°C to -4.1°C over the same span.
December is one of the cooler months of the year in Normal and one of the drier months, so plan for around 2.5°C daytime highs and -5.9°C at night.
Not quite — December is the 3rd coolest month in Normal, averaging -1.7°C.
For December in Normal, pack warm layers and a jacket for chilly mornings, with typical highs of 2.5°C and lows of -5.9°C. Bring an umbrella or light rain jacket too.
Relative humidity in December averages 85% — quite humid.
Average wind speed in December is 3.7 m/s. The windiest December on record averaged 4.8 m/s (2008).
The wettest December on record was 1982 with 174 mm. On average, December sees 63 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 Normal 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.
