December is one of the cooler months of the year in Washington, with average highs near 4.1°C and lows around -3.8°C (mean 0.1°C). It is about average for rainfall, averaging 79 mm of rainfall and 86% relative humidity across the period.
December is one of the cooler months of the year in Washington. Across 45 years of records, the warmest December in Washington was 2015 — when the month averaged 7°C — while the coldest was 1989 at -6.8°C. Typical December days reach 4.1°C with nights near -3.8°C. The long-term trend is warming, about 0.5°C per decade.
December is about average for rainfall in Washington, averaging 79 mm of rainfall. The wettest December on record was 1990 with 186 mm, while the driest was 2006 at 34 mm.
Relative humidity in Washington during December averages 86%. The most humid December was 2012 at 91%, and the least humid was 1998 at 77%.
December receives about 1.4 kWh/m²/day of solar energy in Washington. The sunniest Decembers were 2000 and 2006 at 1.7 kWh/m²/day, and the cloudiest were 2007, 2012 and 2014 at 1.1.
Average wind speed in Washington during December is 0.3 m/s. The windiest Decembers were 2022, 2023 and 2025, among others at 0.3 m/s, while the calmest were 2018, 2021 and 2024, among others at 0.2 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | -1.1°C | 0.4°C | -0.5°C | 0.9°C | 1.5°C | +2.6°C |
| Avg High | 2.7°C | 4.4°C | 3.5°C | 4.7°C | 5.7°C | +3°C |
| Avg Low | -4.9°C | -3.7°C | -4.6°C | -3.0°C | -2.7°C | +2.2°C |
| Avg Rain | 73 mm | 79 mm | 79 mm | 90 mm | 70 mm | -4 mm |
December temperatures in Washington have risen by about 2.2°C between 1981–1985 and 2021–2025.
December has ranged from a record low of -23.3°C (1983) to a record high of 20.9°C (1982).
Rainfall in December is about average for rainfall, averaging 79 mm, with a wettest year of 186 mm.
A quieter season to visit Washington
If your dates are flexible, the more temperate months of August and July tend to be the most comfortable for visiting Washington. That said, December — with days averaging 4.1°C and nights around -3.8°C (mean 0.1°C) and moderate rainfall (79 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 | 3.2°C | -1.2°C | -5.6°C | 14.8°C | -12.1°C | 61 mm | 84% | 0.3 m/s | — |
| 2024 | 5.4°C | 1.5°C | -2.5°C | 16.1°C | -9.8°C | 74 mm | 83% | 0.2 m/s | 1.5 |
| 2023 | 8.1°C | 4.0°C | -0.2°C | 16.2°C | -6.1°C | 71 mm | 86% | 0.3 m/s | 1.3 |
| 2022 | 4.5°C | 0.2°C | -4.1°C | 16.9°C | -19.7°C | 57 mm | 85% | 0.3 m/s | 1.4 |
| 2021 | 9.5°C | 4.6°C | -0.3°C | 17.4°C | -5.8°C | 81 mm | 80% | 0.2 m/s | 1.4 |
| 2020 | 3.6°C | 0.1°C | -3.5°C | 15.4°C | -9.7°C | 74 mm | 88% | 0.3 m/s | 1.2 |
| 2019 | 5.8°C | 1.7°C | -2.4°C | 14.9°C | -13.0°C | 95 mm | 88% | 0.3 m/s | 1.3 |
| 2018 | 4.7°C | 1.0°C | -2.7°C | 15.6°C | -10.6°C | 115 mm | 90% | 0.2 m/s | 1.3 |
| 2017 | 2.3°C | -1.4°C | -5.2°C | 13.1°C | -14.2°C | 36 mm | 79% | 0.3 m/s | 1.5 |
| 2016 | 3.1°C | -0.8°C | -4.8°C | 15.0°C | -15.6°C | 106 mm | 84% | 0.3 m/s | 1.2 |
| 2015 🔥 | 11.4°C | 7.0°C | 2.5°C | 19.6°C | -5.4°C | 96 mm | 87% | 0.3 m/s | 1.2 |
| 2014 | 5.1°C | 1.3°C | -2.5°C | 13.2°C | -7.3°C | 74 mm | 86% | 0.2 m/s | 1.1 |
| 2013 | 3.5°C | -0.2°C | -3.9°C | 18.3°C | -11.4°C | 100 mm | 87% | 0.3 m/s | 1.3 |
| 2012 | 6.6°C | 2.7°C | -1.2°C | 17.8°C | -8.1°C | 145 mm | 91% | 0.3 m/s | 1.1 |
| 2011 | 6.0°C | 2.1°C | -1.9°C | 14.6°C | -7.1°C | 86 mm | 90% | 0.3 m/s | 1.4 |
| 2010 | -1.5°C | -4.6°C | -7.7°C | 9.7°C | -11.3°C | 52 mm | 90% | 0.3 m/s | 1.3 |
| 2009 | 1.9°C | -1.8°C | -5.4°C | 10.0°C | -12.9°C | 100 mm | 86% | 0.3 m/s | 1.4 |
| 2008 | 3.5°C | -0.8°C | -5.2°C | 18.0°C | -15.4°C | 159 mm | 84% | 0.3 m/s | 1.3 |
| 2007 | 4.6°C | 0.7°C | -3.3°C | 15.1°C | -8.5°C | 148 mm | 90% | 0.3 m/s | 1.1 |
| 2006 | 8.0°C | 3.2°C | -1.7°C | 20.5°C | -9.6°C | 34 mm | 80% | 0.3 m/s | 1.7 |
| 2005 | 0.7°C | -3.1°C | -7.0°C | 11.4°C | -16.1°C | 49 mm | 90% | 0.3 m/s | 1.3 |
| 2004 | 4.5°C | 0.4°C | -3.8°C | 17.9°C | -13.6°C | 60 mm | 85% | 0.3 m/s | 1.4 |
| 2003 | 2.9°C | -0.5°C | -4.0°C | 12.3°C | -10.4°C | 67 mm | 87% | 0.3 m/s | 1.3 |
| 2002 | 1.9°C | -1.6°C | -5.1°C | 11.0°C | -12.1°C | 62 mm | 87% | 0.3 m/s | 1.4 |
| 2001 | 7.4°C | 3.1°C | -1.2°C | 20.7°C | -10.4°C | 58 mm | 80% | 0.3 m/s | 1.5 |
| 2000 | -0.7°C | -4.8°C | -8.9°C | 8.1°C | -15.6°C | 47 mm | 81% | 0.3 m/s | 1.7 |
| 1999 | 5.0°C | 0.9°C | -3.3°C | 16.9°C | -12.4°C | 55 mm | 81% | 0.3 m/s | 1.4 |
| 1998 | 7.3°C | 2.5°C | -2.3°C | 20.5°C | -13.4°C | 42 mm | 77% | 0.3 m/s | 1.4 |
| 1997 | 3.6°C | 0.1°C | -3.3°C | 10.2°C | -12.4°C | 40 mm | 87% | 0.2 m/s | 1.5 |
| 1996 | 5.2°C | 1.2°C | -2.7°C | 15.3°C | -13.1°C | 67 mm | 90% | 0.2 m/s | 1.2 |
| 1995 | -0.2°C | -3.8°C | -7.4°C | 10.1°C | -15.9°C | 61 mm | 87% | 0.2 m/s | 1.5 |
| 1994 | 7.2°C | 2.6°C | -2.0°C | 15.4°C | -7.3°C | 73 mm | 84% | 0.2 m/s | 1.4 |
| 1993 | 2.6°C | -1.0°C | -4.6°C | 10.6°C | -13.7°C | 57 mm | 87% | 0.3 m/s | 1.2 |
| 1992 | 2.4°C | -1.0°C | -4.5°C | 14.1°C | -10.8°C | 92 mm | 89% | 0.2 m/s | 1.2 |
| 1991 | 4.7°C | 0.6°C | -3.5°C | 16.7°C | -12.8°C | 117 mm | 85% | 0.3 m/s | 1.4 |
| 1990 🌧️ | 6.5°C | 1.7°C | -3.0°C | 15.9°C | -12.0°C | 186 mm | 87% | 0.3 m/s | 1.4 |
| 1989 ❄️ | -2.9°C | -6.8°C | -10.7°C | 6.7°C | -22.3°C | 58 mm | 87% | 0.3 m/s | 1.6 |
| 1988 | 2.8°C | -1.2°C | -5.3°C | 13.8°C | -11.7°C | 56 mm | 79% | 0.2 m/s | 1.5 |
| 1987 | 4.3°C | 0.5°C | -3.3°C | 13.4°C | -8.9°C | 80 mm | 87% | 0.3 m/s | 1.3 |
| 1986 | 3.2°C | -0.4°C | -4.0°C | 13.2°C | -10.6°C | 84 mm | 88% | 0.2 m/s | 1.2 |
| 1985 | 0.6°C | -3.3°C | -7.1°C | 13.3°C | -16.9°C | 52 mm | 89% | 0.3 m/s | 1.5 |
| 1984 | 7.7°C | 3.5°C | -0.8°C | 18.1°C | -10.5°C | 85 mm | 88% | 0.2 m/s | 1.2 |
| 1983 | -0.6°C | -4.1°C | -7.6°C | 13.1°C | -23.3°C | 103 mm | 88% | 0.3 m/s | — |
| 1982 | 7.9°C | 3.8°C | -0.3°C | 20.9°C | -9.2°C | 70 mm | 85% | 0.3 m/s | — |
| 1981 | 1.3°C | -2.0°C | -5.3°C | 6.6°C | -14.3°C | 71 mm | 87% | 0.3 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around 4.1°C with lows near -3.8°C (mean 0.1°C), based on 45 years of NASA POWER data.
December averages 79 mm of rainfall in Washington, about average for rainfall. The wettest on record was 186 mm in 1990.
The hottest December reached 20.9°C in 1982. The coldest dipped to -23.3°C in 1983.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 2.2°C. Daytime highs moved from 3.4°C to 6.1°C and overnight lows from -4.2°C to -2.5°C over the same span.
December is one of the cooler months of the year in Washington and about average for rainfall, so plan for around 4.1°C daytime highs and -3.8°C at night.
Not quite — December is the 3rd coolest month in Washington, averaging 0.1°C.
For December in Washington, pack warm layers and a jacket for chilly mornings, with typical highs of 4.1°C and lows of -3.8°C. Bring an umbrella or light rain jacket too.
Relative humidity in December averages 86% — quite humid.
Average wind speed in December is 0.3 m/s. The windiest December on record averaged 0.3 m/s (1981).
The wettest December on record was 1990 with 186 mm. On average, December sees 79 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 Washington 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.
