December is one of the cooler months of the year in Chambersburg, with average highs near 3.9°C and lows around -4.1°C (mean -0.1°C). It is about average for rainfall, averaging 82 mm of rainfall and 86% relative humidity across the period.
December is one of the cooler months of the year in Chambersburg. Across 45 years of records, the warmest December in Chambersburg was 2015 — when the month averaged 6.6°C — while the coldest was 1989 at -6.2°C. Typical December days reach 3.9°C with nights near -4.1°C. The long-term trend is warming, about 0.4°C per decade.
December is about average for rainfall in Chambersburg, averaging 82 mm of rainfall. The wettest Decembers on record were 1990 and 2018 with 153 mm, while the driest was 1998 at 17 mm.
Relative humidity in Chambersburg during December averages 86%. The most humid December was 1996 at 92%, and the least humid was 1998 at 71%.
December receives about 1.7 kWh/m²/day of solar energy in Chambersburg. The sunniest December was 2006 at 2.1 kWh/m²/day, and the cloudiest were 2012, 2014 and 2015, among others at 1.5.
Average wind speed in Chambersburg during December is 1.1 m/s. The windiest December was 2010 at 1.5 m/s, while the calmest was 2023 at 0.9 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | -1.2°C | 0.4°C | -0.9°C | 0.8°C | 0.7°C | +1.9°C |
| Avg High | 2.7°C | 4.5°C | 3.2°C | 4.6°C | 5.0°C | +2.3°C |
| Avg Low | -5.2°C | -3.6°C | -5.0°C | -3.0°C | -3.6°C | +1.6°C |
| Avg Rain | 64 mm | 83 mm | 90 mm | 84 mm | 87 mm | +24 mm |
December temperatures in Chambersburg have risen by about 1.6°C between 1981–1985 and 2021–2025.
December has ranged from a record low of -26.4°C (1983) to a record high of 23°C (2001).
Rainfall in December is about average for rainfall, averaging 82 mm, with a wettest year of 153 mm.
A quieter season to visit Chambersburg
If your dates are flexible, the more temperate months of August and June tend to be the most comfortable for visiting Chambersburg. That said, December — with days averaging 3.9°C and nights around -4.1°C (mean -0.1°C) and higher rainfall (82 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 | 2.3°C | -1.7°C | -5.8°C | 9.6°C | -13.0°C | 49 mm | 80% | 1.3 m/s | — |
| 2024 | 4.5°C | 0.4°C | -3.7°C | 14.8°C | -13.0°C | 82 mm | 83% | 1.1 m/s | 1.7 |
| 2023 | 7.4°C | 3.2°C | -1.0°C | 12.0°C | -5.6°C | 129 mm | 89% | 0.9 m/s | 1.6 |
| 2022 | 2.9°C | -1.6°C | -6.1°C | 15.2°C | -20.4°C | 120 mm | 89% | 1 m/s | 1.9 |
| 2021 | 8.7°C | 3.9°C | -0.9°C | 16.4°C | -6.0°C | 32 mm | 83% | 1 m/s | 1.8 |
| 2020 | 4.0°C | -0.2°C | -4.3°C | 13.0°C | -13.7°C | 112 mm | 88% | 1.1 m/s | 1.8 |
| 2019 | 4.2°C | 0.5°C | -3.3°C | 14.6°C | -13.6°C | 87 mm | 88% | 1 m/s | 1.7 |
| 2018 | 4.7°C | 1.2°C | -2.4°C | 15.8°C | -8.6°C | 153 mm | 91% | 1 m/s | 1.7 |
| 2017 | 2.5°C | -1.1°C | -4.6°C | 10.4°C | -13.3°C | 28 mm | 80% | 1.1 m/s | 1.8 |
| 2016 | 3.4°C | -0.5°C | -4.3°C | 11.5°C | -13.9°C | 63 mm | 81% | 1.2 m/s | 1.7 |
| 2015 🔥 | 10.8°C | 6.6°C | 2.5°C | 20.3°C | -5.0°C | 97 mm | 89% | 1 m/s | 1.5 |
| 2014 | 4.4°C | 0.9°C | -2.6°C | 14.6°C | -6.5°C | 68 mm | 86% | 1 m/s | 1.5 |
| 2013 | 3.1°C | -1.0°C | -5.1°C | 19.2°C | -13.6°C | 102 mm | 92% | 1 m/s | 1.6 |
| 2012 | 6.3°C | 2.3°C | -1.7°C | 18.0°C | -10.8°C | 98 mm | 90% | 1.1 m/s | 1.5 |
| 2011 | 5.9°C | 2.0°C | -1.9°C | 14.3°C | -6.4°C | 87 mm | 90% | 1 m/s | 1.8 |
| 2010 | 0.3°C | -3.1°C | -6.5°C | 14.2°C | -10.7°C | 61 mm | 82% | 1.5 m/s | 1.8 |
| 2009 | 1.5°C | -2.4°C | -6.2°C | 10.8°C | -15.2°C | 143 mm | 89% | 1.2 m/s | 1.8 |
| 2008 | 2.4°C | -1.4°C | -5.2°C | 13.0°C | -14.0°C | 143 mm | 87% | 1.3 m/s | 1.6 |
| 2007 | 3.1°C | -0.5°C | -4.1°C | 12.8°C | -12.7°C | 117 mm | 90% | 1.1 m/s | 1.5 |
| 2006 | 7.8°C | 3.1°C | -1.7°C | 21.2°C | -10.1°C | 57 mm | 85% | 1.1 m/s | 2.1 |
| 2005 | 1.0°C | -3.0°C | -7.0°C | 9.0°C | -14.3°C | 57 mm | 89% | 1.1 m/s | 1.9 |
| 2004 | 4.4°C | 0.3°C | -3.9°C | 13.6°C | -14.9°C | 78 mm | 85% | 1.2 m/s | 1.8 |
| 2003 | 2.8°C | -1.1°C | -4.9°C | 8.4°C | -11.8°C | 106 mm | 88% | 1.2 m/s | 1.9 |
| 2002 | 1.1°C | -2.8°C | -6.7°C | 7.4°C | -13.6°C | 96 mm | 89% | 1.1 m/s | 1.8 |
| 2001 | 7.7°C | 3.2°C | -1.2°C | 23.0°C | -10.2°C | 43 mm | 77% | 1.1 m/s | 2 |
| 2000 | 0.0°C | -4.3°C | -8.6°C | 9.9°C | -15.9°C | 64 mm | 79% | 1.2 m/s | 1.9 |
| 1999 | 5.4°C | 1.0°C | -3.4°C | 16.4°C | -10.7°C | 61 mm | 83% | 1 m/s | 1.8 |
| 1998 | 8.6°C | 3.6°C | -1.3°C | 22.7°C | -11.5°C | 17 mm | 71% | 1.1 m/s | 1.8 |
| 1997 | 4.0°C | 0.3°C | -3.4°C | 11.3°C | -9.0°C | 49 mm | 88% | 1.1 m/s | 1.9 |
| 1996 | 4.1°C | 0.6°C | -2.8°C | 11.7°C | -13.2°C | 126 mm | 92% | 1.1 m/s | 1.6 |
| 1995 | -0.1°C | -4.0°C | -7.8°C | 9.6°C | -15.1°C | 57 mm | 88% | 1.2 m/s | 1.9 |
| 1994 | 6.3°C | 2.0°C | -2.2°C | 16.7°C | -7.6°C | 70 mm | 86% | 1.1 m/s | 1.7 |
| 1993 | 2.7°C | -1.1°C | -5.0°C | 10.3°C | -12.6°C | 89 mm | 87% | 1.2 m/s | 1.6 |
| 1992 | 2.9°C | -0.6°C | -4.1°C | 16.3°C | -11.4°C | 116 mm | 88% | 1.2 m/s | 1.6 |
| 1991 | 4.9°C | 0.8°C | -3.3°C | 15.7°C | -12.0°C | 88 mm | 83% | 1.2 m/s | 1.9 |
| 1990 🌧️ | 5.7°C | 1.3°C | -3.2°C | 15.3°C | -9.8°C | 153 mm | 88% | 1.2 m/s | 1.6 |
| 1989 ❄️ | -2.3°C | -6.2°C | -10.2°C | 4.8°C | -17.9°C | 33 mm | 83% | 1.2 m/s | 1.9 |
| 1988 | 2.9°C | -1.3°C | -5.4°C | 11.3°C | -13.9°C | 32 mm | 78% | 1.1 m/s | 1.8 |
| 1987 | 4.5°C | 0.6°C | -3.3°C | 12.0°C | -10.9°C | 51 mm | 86% | 1.1 m/s | 1.5 |
| 1986 | 3.5°C | -0.2°C | -3.9°C | 8.7°C | -9.4°C | 107 mm | 87% | 1 m/s | 1.9 |
| 1985 | 1.4°C | -2.5°C | -6.5°C | 8.6°C | -16.2°C | 34 mm | 85% | 1.2 m/s | 1.7 |
| 1984 | 6.5°C | 2.3°C | -1.8°C | 19.3°C | -9.4°C | 53 mm | 89% | 1 m/s | 1.5 |
| 1983 | 0.1°C | -4.0°C | -8.0°C | 11.8°C | -26.4°C | 151 mm | 88% | 1.2 m/s | — |
| 1982 | 6.8°C | 2.6°C | -1.6°C | 20.9°C | -8.4°C | 49 mm | 85% | 1.1 m/s | — |
| 1981 | 1.0°C | -2.5°C | -6.0°C | 6.8°C | -15.2°C | 62 mm | 87% | 1.2 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around 3.9°C with lows near -4.1°C (mean -0.1°C), based on 45 years of NASA POWER data.
December averages 82 mm of rainfall in Chambersburg, about average for rainfall. The wettest on record was 153 mm in 1990.
The hottest December reached 23°C in 2001. The coldest dipped to -26.4°C in 1983.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 1.6°C. Daytime highs moved from 3.2°C to 5.2°C and overnight lows from -4.8°C to -3.5°C over the same span.
December is one of the cooler months of the year in Chambersburg and about average for rainfall, so plan for around 3.9°C daytime highs and -4.1°C at night.
Not quite — December is the 3rd coolest month in Chambersburg, averaging -0.1°C.
For December in Chambersburg, pack warm layers and a jacket for chilly mornings, with typical highs of 3.9°C and lows of -4.1°C. Bring an umbrella or light rain jacket too.
Relative humidity in December averages 86% — quite humid.
Average wind speed in December is 1.1 m/s. The windiest December on record averaged 1.5 m/s (2010).
The wettest December on record was 1990 with 153 mm. On average, December sees 82 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 Chambersburg 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.
