December is one of the cooler months of the year in Killeen, with average highs near 16.4°C and lows around 4.2°C (mean 10.3°C). It is one of the drier months, averaging 54 mm of rainfall and 72% relative humidity across the period.
December is one of the cooler months of the year in Killeen. Across 45 years of records, the warmest December in Killeen was 2021 — when the month averaged 17.2°C — while the coldest was 1983 at 4.4°C. Typical December days reach 16.4°C with nights near 4.2°C. The long-term trend is warming, about 0.8°C per decade.
December is one of the drier months in Killeen, averaging 54 mm of rainfall. The wettest December on record was 1991 with 266 mm, while the driest was 2025 at 3 mm.
Relative humidity in Killeen during December averages 72%. The most humid December was 1986 at 84%, and the least humid was 2005 at 59%.
December receives about 2.7 kWh/m²/day of solar energy in Killeen. The sunniest Decembers were 1985, 2003 and 2023 at 3.2 kWh/m²/day, and the cloudiest were 1992 and 2014 at 2.
Average wind speed in Killeen during December is 2.9 m/s. The windiest December was 2008 at 3.5 m/s, while the calmest was 1986 at 2.2 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 8.8°C | 10.3°C | 9.7°C | 10.6°C | 13.1°C | +4.3°C |
| Avg High | 14.7°C | 16.3°C | 16.0°C | 16.5°C | 19.6°C | +4.9°C |
| Avg Low | 2.8°C | 4.2°C | 3.3°C | 4.7°C | 6.6°C | +3.8°C |
| Avg Rain | 55 mm | 85 mm | 42 mm | 49 mm | 32 mm | -23 mm |
December temperatures in Killeen have risen by about 4.5°C between 1981–1985 and 2021–2025.
December has ranged from a record low of -16.7°C (1989) to a record high of 29.4°C (2025).
Rainfall in December is one of the drier months, averaging 54 mm, with a wettest year of 266 mm.
Daytime highs and overnight lows have shifted differently — highs rose about 0.9°C per decade while lows rose 0.7°C per decade, widening the gap between day and night.
A quieter season to visit Killeen
If your dates are flexible, the more temperate months of October and April tend to be the most comfortable for visiting Killeen. That said, December — with days averaging 16.4°C and nights around 4.2°C (mean 10.3°C) and moderate rainfall (54 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 | 19.5°C | 12.8°C | 6.0°C | 29.4°C | -2.4°C | 3 mm | 68% | 2.7 m/s | — |
| 2024 | 20.7°C | 14.2°C | 7.7°C | 29.3°C | 0.5°C | 31 mm | 70% | 2.6 m/s | 2.7 |
| 2023 | 19.1°C | 12.5°C | 5.9°C | 25.8°C | -0.4°C | 60 mm | 68% | 2.5 m/s | 3.2 |
| 2022 | 16.8°C | 11.1°C | 5.4°C | 26.6°C | -10.1°C | 22 mm | 73% | 2.7 m/s | 2.4 |
| 2021 🔥 | 23.4°C | 17.2°C | 11.1°C | 29.0°C | 0.5°C | 16 mm | 75% | 2.8 m/s | 2.8 |
| 2020 | 17.9°C | 10.7°C | 3.4°C | 25.9°C | -2.1°C | 62 mm | 67% | 2.8 m/s | 3 |
| 2019 | 18.4°C | 11.4°C | 4.5°C | 27.7°C | -1.9°C | 18 mm | 67% | 2.5 m/s | 3.1 |
| 2018 | 15.0°C | 9.9°C | 4.7°C | 22.9°C | -1.1°C | 110 mm | 77% | 3.1 m/s | 2.6 |
| 2017 | 15.7°C | 10.1°C | 4.5°C | 28.3°C | -3.4°C | 56 mm | 69% | 2.7 m/s | 2.3 |
| 2016 | 16.0°C | 10.7°C | 5.4°C | 26.6°C | -6.7°C | 46 mm | 74% | 3.1 m/s | 2.2 |
| 2015 | 18.5°C | 12.3°C | 6.1°C | 25.5°C | -1.3°C | 63 mm | 78% | 2.7 m/s | 2.9 |
| 2014 | 16.2°C | 11.3°C | 6.3°C | 25.3°C | -1.2°C | 22 mm | 78% | 2.8 m/s | 2 |
| 2013 | 13.8°C | 7.8°C | 1.8°C | 25.9°C | -6.1°C | 32 mm | 76% | 2.6 m/s | 2.7 |
| 2012 | 19.0°C | 12.4°C | 5.7°C | 28.3°C | -5.2°C | 15 mm | 62% | 3 m/s | 2.8 |
| 2011 | 15.1°C | 9.7°C | 4.3°C | 23.5°C | -5.9°C | 100 mm | 77% | 2.8 m/s | 2.1 |
| 2010 | 17.5°C | 10.6°C | 3.6°C | 28.8°C | -4.7°C | 23 mm | 62% | 3.2 m/s | 3.1 |
| 2009 | 12.6°C | 7.1°C | 1.6°C | 22.4°C | -5.2°C | 40 mm | 78% | 2.7 m/s | 2.5 |
| 2008 | 17.4°C | 10.5°C | 3.5°C | 26.6°C | -2.7°C | 9 mm | 60% | 3.5 m/s | 2.9 |
| 2007 | 17.5°C | 10.6°C | 3.6°C | 26.3°C | -4.4°C | 24 mm | 71% | 3 m/s | 2.9 |
| 2006 | 17.3°C | 10.9°C | 4.6°C | 25.7°C | -4.7°C | 56 mm | 69% | 2.8 m/s | 3 |
| 2005 | 16.7°C | 9.9°C | 3.1°C | 28.2°C | -4.9°C | 4 mm | 59% | 2.7 m/s | 3 |
| 2004 | 15.9°C | 9.7°C | 3.5°C | 23.0°C | -6.1°C | 18 mm | 75% | 2.8 m/s | 3.1 |
| 2003 | 17.8°C | 10.9°C | 4.0°C | 24.3°C | -2.4°C | 16 mm | 65% | 3.3 m/s | 3.2 |
| 2002 | 16.2°C | 10.2°C | 4.2°C | 22.5°C | -3.7°C | 113 mm | 78% | 3 m/s | 2.6 |
| 2001 | 17.0°C | 10.9°C | 4.8°C | 25.5°C | -3.5°C | 84 mm | 74% | 2.8 m/s | 2.7 |
| 2000 | 11.7°C | 5.9°C | 0.0°C | 22.4°C | -5.1°C | 60 mm | 78% | 2.9 m/s | 2.4 |
| 1999 | 18.4°C | 11.2°C | 4.0°C | 27.3°C | -3.0°C | 43 mm | 62% | 3.2 m/s | 3 |
| 1998 | 15.4°C | 9.8°C | 4.2°C | 26.2°C | -4.9°C | 62 mm | 79% | 3.1 m/s | 2.4 |
| 1997 | 15.0°C | 8.6°C | 2.3°C | 24.2°C | -4.8°C | 130 mm | 72% | 2.9 m/s | 2.9 |
| 1996 | 17.3°C | 10.5°C | 3.7°C | 26.3°C | -6.7°C | 58 mm | 75% | 3.1 m/s | 2.9 |
| 1995 | 17.2°C | 10.9°C | 4.5°C | 27.2°C | -6.2°C | 27 mm | 70% | 2.9 m/s | 2.8 |
| 1994 | 16.9°C | 11.2°C | 5.6°C | 25.3°C | -1.7°C | 111 mm | 81% | 2.3 m/s | 2.4 |
| 1993 | 15.6°C | 9.8°C | 4.1°C | 23.5°C | -4.4°C | 44 mm | 73% | 2.9 m/s | 2.5 |
| 1992 | 15.7°C | 10.3°C | 4.9°C | 24.7°C | -1.3°C | 84 mm | 81% | 2.9 m/s | 2 |
| 1991 🌧️ | 15.6°C | 10.8°C | 6.1°C | 23.6°C | -1.2°C | 266 mm | 82% | 2.9 m/s | 2.3 |
| 1990 | 16.0°C | 9.5°C | 2.9°C | 25.8°C | -8.3°C | 21 mm | 70% | 3.1 m/s | 2.7 |
| 1989 | 11.6°C | 5.0°C | -1.7°C | 24.2°C | -16.7°C | 6 mm | 61% | 3.3 m/s | 3.1 |
| 1988 | 17.2°C | 10.8°C | 4.4°C | 24.4°C | -3.1°C | 44 mm | 69% | 2.9 m/s | 2.5 |
| 1987 | 15.6°C | 9.5°C | 3.4°C | 24.6°C | -4.4°C | 66 mm | 75% | 3 m/s | 2.4 |
| 1986 | 13.0°C | 8.1°C | 3.3°C | 20.3°C | -2.1°C | 127 mm | 84% | 2.2 m/s | 2.3 |
| 1985 | 14.0°C | 7.6°C | 1.2°C | 23.0°C | -6.7°C | 56 mm | 77% | 2.8 m/s | 3.2 |
| 1984 | 19.0°C | 13.8°C | 8.6°C | 24.2°C | -3.6°C | 104 mm | 82% | 3 m/s | 2.2 |
| 1983 ❄️ | 10.3°C | 4.4°C | -1.4°C | 26.0°C | -13.1°C | 18 mm | 67% | 3.3 m/s | — |
| 1982 | 15.6°C | 9.8°C | 4.0°C | 26.3°C | -4.4°C | 65 mm | 74% | 3.3 m/s | — |
| 1981 | 16.4°C | 10.0°C | 3.6°C | 25.7°C | -5.6°C | 10 mm | 72% | 3 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around 16.4°C with lows near 4.2°C (mean 10.3°C), based on 45 years of NASA POWER data.
December averages 54 mm of rainfall in Killeen, one of the drier months. The wettest on record was 266 mm in 1991.
The hottest December reached 29.4°C in 2025. The coldest dipped to -16.7°C in 1989.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 4.5°C. Daytime highs moved from 15.1°C to 19.9°C and overnight lows from 3.2°C to 7.2°C over the same span.
December is one of the cooler months of the year in Killeen and one of the drier months, so plan for around 16.4°C daytime highs and 4.2°C at night.
Not quite — December is the 2nd coolest month in Killeen, averaging 10.3°C.
For December in Killeen, pack warm layers and a jacket for chilly mornings, with typical highs of 16.4°C and lows of 4.2°C. Bring an umbrella or light rain jacket too.
Relative humidity in December averages 72% — moderately humid.
Average wind speed in December is 2.9 m/s. The windiest December on record averaged 3.5 m/s (2008).
The wettest December on record was 1991 with 266 mm. On average, December sees 54 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 Killeen 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.
