December is one of the cooler months of the year in Knoxville, with average highs near 9.7°C and lows around -0.5°C (mean 4.6°C). It is a relatively wet time of year, averaging 116 mm of rainfall and 82% relative humidity across the period.
December is one of the cooler months of the year in Knoxville. Across 45 years of records, the warmest December in Knoxville was 2015 — when the month averaged 10.7°C — while the coldest was 1989 at -1.9°C. Typical December days reach 9.7°C with nights near -0.5°C. The long-term trend is warming, about 0.7°C per decade.
December is a relatively wet time of year in Knoxville, averaging 116 mm of rainfall. The wettest December on record was 1990 with 238 mm, while the driest was 1985 at 43 mm.
Relative humidity in Knoxville during December averages 82%. The most humid December was 1982 at 88%, and the least humid was 1999 at 72%.
December receives about 2.1 kWh/m²/day of solar energy in Knoxville. The sunniest December was 2006 at 2.6 kWh/m²/day, and the cloudiest was 1992 at 1.7.
Average wind speed in Knoxville during December is 0.9 m/s. The windiest Decembers were 2004, 2008 and 2021, among others at 1 m/s, while the calmest were 2011, 2014 and 2018, among others at 0.8 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 3.2°C | 4.7°C | 4.0°C | 5.5°C | 6.1°C | +2.9°C |
| Avg High | 8.2°C | 9.8°C | 9.2°C | 10.4°C | 11.6°C | +3.4°C |
| Avg Low | -1.8°C | -0.5°C | -1.3°C | 0.6°C | 0.7°C | +2.5°C |
| Avg Rain | 99 mm | 127 mm | 107 mm | 135 mm | 109 mm | +10 mm |
December temperatures in Knoxville have risen by about 3°C between 1981–1985 and 2021–2025.
December has ranged from a record low of -19.3°C (1983) to a record high of 23.4°C (2001).
Rainfall in December is a relatively wet time of year, averaging 116 mm, with a wettest year of 238 mm.
A quieter season to visit Knoxville
If your dates are flexible, the more temperate months of September and June tend to be the most comfortable for visiting Knoxville. That said, December — with days averaging 9.7°C and nights around -0.5°C (mean 4.6°C) and higher rainfall (116 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 | 10.8°C | 5.3°C | -0.2°C | 20.9°C | -9.5°C | 52 mm | 77% | 0.9 m/s | — |
| 2024 | 11.4°C | 5.9°C | 0.5°C | 20.8°C | -7.4°C | 118 mm | 77% | 0.9 m/s | 2.2 |
| 2023 | 12.5°C | 6.8°C | 1.1°C | 19.5°C | -6.5°C | 141 mm | 76% | 0.9 m/s | 2.3 |
| 2022 | 10.0°C | 4.9°C | -0.2°C | 19.5°C | -15.9°C | 137 mm | 83% | 0.9 m/s | 2.1 |
| 2021 | 15.8°C | 10.0°C | 4.2°C | 20.9°C | -4.3°C | 98 mm | 81% | 1 m/s | 2.1 |
| 2020 | 9.3°C | 4.0°C | -1.3°C | 17.7°C | -8.1°C | 105 mm | 83% | 0.9 m/s | 2.3 |
| 2019 | 12.4°C | 7.4°C | 2.3°C | 20.5°C | -5.5°C | 127 mm | 82% | 0.9 m/s | 2.3 |
| 2018 | 9.6°C | 5.3°C | 0.9°C | 19.5°C | -7.0°C | 179 mm | 86% | 0.8 m/s | 1.9 |
| 2017 | 8.9°C | 4.0°C | -0.9°C | 18.1°C | -10.5°C | 81 mm | 78% | 0.9 m/s | 2.1 |
| 2016 | 9.7°C | 4.5°C | -0.7°C | 20.8°C | -7.7°C | 158 mm | 82% | 0.9 m/s | 2.1 |
| 2015 🔥 | 15.6°C | 10.7°C | 5.9°C | 22.8°C | -5.1°C | 207 mm | 87% | 0.9 m/s | 2 |
| 2014 | 10.9°C | 5.9°C | 1.0°C | 18.7°C | -4.9°C | 103 mm | 84% | 0.8 m/s | 1.9 |
| 2013 | 10.0°C | 5.0°C | 0.0°C | 22.1°C | -6.4°C | 182 mm | 83% | 0.9 m/s | 2.1 |
| 2012 | 12.4°C | 7.1°C | 1.9°C | 21.7°C | -5.9°C | 134 mm | 81% | 0.9 m/s | 1.9 |
| 2011 | 11.6°C | 6.2°C | 0.9°C | 17.7°C | -5.7°C | 125 mm | 85% | 0.8 m/s | 2.2 |
| 2010 | 2.9°C | -1.1°C | -5.2°C | 13.6°C | -11.0°C | 57 mm | 82% | 0.9 m/s | 2.1 |
| 2009 | 7.0°C | 2.3°C | -2.4°C | 15.0°C | -7.7°C | 162 mm | 86% | 0.9 m/s | 2.1 |
| 2008 | 10.3°C | 4.8°C | -0.7°C | 18.8°C | -10.9°C | 180 mm | 82% | 1 m/s | 1.9 |
| 2007 | 13.0°C | 7.4°C | 1.8°C | 23.2°C | -5.6°C | 85 mm | 80% | 0.9 m/s | 2 |
| 2006 | 12.8°C | 6.7°C | 0.6°C | 19.6°C | -7.9°C | 56 mm | 79% | 0.9 m/s | 2.6 |
| 2005 | 7.0°C | 2.1°C | -2.9°C | 15.5°C | -6.5°C | 79 mm | 80% | 0.9 m/s | 2.2 |
| 2004 | 9.3°C | 4.0°C | -1.3°C | 20.8°C | -10.7°C | 125 mm | 81% | 1 m/s | 2.4 |
| 2003 | 8.0°C | 2.8°C | -2.5°C | 15.5°C | -6.5°C | 85 mm | 81% | 0.9 m/s | 2.3 |
| 2002 | 7.6°C | 3.0°C | -1.6°C | 15.0°C | -9.9°C | 138 mm | 87% | 0.9 m/s | 2.2 |
| 2001 | 12.3°C | 6.9°C | 1.5°C | 23.4°C | -8.1°C | 103 mm | 77% | 0.9 m/s | 2.5 |
| 2000 | 5.1°C | -0.2°C | -5.5°C | 16.5°C | -11.7°C | 59 mm | 78% | 0.9 m/s | 2.3 |
| 1999 | 11.3°C | 5.3°C | -0.6°C | 19.4°C | -7.1°C | 45 mm | 72% | 0.9 m/s | 2.4 |
| 1998 | 11.3°C | 5.9°C | 0.5°C | 22.9°C | -14.8°C | 169 mm | 83% | 0.9 m/s | 2 |
| 1997 | 8.0°C | 3.5°C | -1.1°C | 15.6°C | -8.6°C | 67 mm | 84% | 0.9 m/s | 2 |
| 1996 | 10.6°C | 5.2°C | -0.1°C | 20.0°C | -10.4°C | 104 mm | 83% | 1 m/s | 2.1 |
| 1995 | 7.0°C | 1.9°C | -3.2°C | 18.3°C | -14.1°C | 64 mm | 82% | 0.9 m/s | 2.3 |
| 1994 | 12.0°C | 6.5°C | 1.0°C | 18.9°C | -5.1°C | 52 mm | 82% | 0.8 m/s | 2.1 |
| 1993 | 7.7°C | 3.0°C | -1.7°C | 15.6°C | -9.1°C | 164 mm | 84% | 0.9 m/s | 2.1 |
| 1992 | 8.0°C | 3.5°C | -1.0°C | 16.6°C | -6.0°C | 153 mm | 87% | 0.8 m/s | 1.7 |
| 1991 | 10.7°C | 5.5°C | 0.2°C | 21.0°C | -6.5°C | 216 mm | 84% | 0.9 m/s | 2.2 |
| 1990 🌧️ | 11.7°C | 6.3°C | 1.0°C | 20.4°C | -7.5°C | 238 mm | 83% | 1 m/s | 1.9 |
| 1989 ❄️ | 2.7°C | -1.9°C | -6.5°C | 14.9°C | -19.0°C | 89 mm | 84% | 1 m/s | 2.1 |
| 1988 | 8.8°C | 3.4°C | -2.0°C | 17.4°C | -6.8°C | 99 mm | 80% | 0.9 m/s | 2.3 |
| 1987 | 11.5°C | 5.7°C | -0.1°C | 21.0°C | -6.2°C | 100 mm | 77% | 1 m/s | 1.9 |
| 1986 | 8.4°C | 3.7°C | -1.0°C | 17.7°C | -7.2°C | 106 mm | 85% | 0.8 m/s | 1.9 |
| 1985 | 5.9°C | 0.9°C | -4.2°C | 17.1°C | -12.5°C | 43 mm | 78% | 1 m/s | 2.3 |
| 1984 | 13.9°C | 8.5°C | 3.1°C | 20.9°C | -9.8°C | 66 mm | 86% | 0.9 m/s | 2.1 |
| 1983 | 6.6°C | 1.4°C | -3.8°C | 18.4°C | -19.3°C | 155 mm | 80% | 1 m/s | — |
| 1982 | 11.2°C | 6.5°C | 1.9°C | 21.9°C | -9.6°C | 128 mm | 88% | 0.9 m/s | — |
| 1981 | 5.2°C | 0.7°C | -3.8°C | 15.9°C | -13.2°C | 101 mm | 83% | 0.9 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around 9.7°C with lows near -0.5°C (mean 4.6°C), based on 45 years of NASA POWER data.
December averages 116 mm of rainfall in Knoxville, a relatively wet time of year. The wettest on record was 238 mm in 1990.
The hottest December reached 23.4°C in 2001. The coldest dipped to -19.3°C in 1983.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 3°C. Daytime highs moved from 8.6°C to 12.1°C and overnight lows from -1.4°C to 1.1°C over the same span.
December is one of the cooler months of the year in Knoxville and a relatively wet time of year, so plan for around 9.7°C daytime highs and -0.5°C at night.
Not quite — December is the 2nd coolest month in Knoxville, averaging 4.6°C.
For December in Knoxville, pack warm layers and a jacket for chilly mornings, with typical highs of 9.7°C and lows of -0.5°C. Bring an umbrella or light rain jacket too.
Relative humidity in December averages 82% — quite humid.
Average wind speed in December is 0.9 m/s. The windiest December on record averaged 1 m/s (1983).
The wettest December on record was 1990 with 238 mm. On average, December sees 116 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 Knoxville 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.
