December is one of the cooler months of the year in Watertown, with average highs near -0.4°C and lows around -7.3°C (mean -3.8°C). It is about average for rainfall, averaging 92 mm of rainfall and 91% relative humidity across the period.
December is one of the cooler months of the year in Watertown. Across 45 years of records, the warmest December in Watertown was 2015 — when the month averaged 2.9°C — while the coldest was 1989 at -12.8°C. Typical December days reach -0.4°C with nights near -7.3°C. The long-term trend is warming, about 0.5°C per decade.
December is about average for rainfall in Watertown, averaging 92 mm of rainfall. The wettest December on record was 1983 with 181 mm, while the driest was 1989 at 50 mm.
Relative humidity in Watertown during December averages 91%. The most humid December was 1983 at 98%, and the least humid was 2021 at 85%.
December receives about 1.1 kWh/m²/day of solar energy in Watertown. The sunniest December was 1989 at 1.4 kWh/m²/day, and the cloudiest were 2015, 2020 and 2023, among others at 0.9.
Average wind speed in Watertown during December is 0.9 m/s. The windiest December was 2008 at 1.1 m/s, while the calmest was 2023 at 0.7 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | -5.3°C | -3.6°C | -4.4°C | -3.3°C | -2.4°C | +2.9°C |
| Avg High | -1.8°C | 0.0°C | -1.0°C | 0.1°C | 0.9°C | +2.7°C |
| Avg Low | -8.8°C | -7.2°C | -7.9°C | -6.6°C | -5.6°C | +3.2°C |
| Avg Rain | 90 mm | 85 mm | 104 mm | 86 mm | 96 mm | +7 mm |
December temperatures in Watertown have risen by about 2.1°C between 1981–1985 and 2021–2025.
December has ranged from a record low of -29.9°C (1983) to a record high of 17.2°C (2012).
Rainfall in December is about average for rainfall, averaging 92 mm, with a wettest year of 181 mm.
A quieter season to visit Watertown
If your dates are flexible, the more temperate months of July and August tend to be the most comfortable for visiting Watertown. That said, December — with days averaging -0.4°C and nights around -7.3°C (mean -3.8°C) and higher rainfall (92 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 | -6.4°C | -10.6°C | 8.6°C | -19.6°C | 93 mm | 90% | 1 m/s | — |
| 2024 | 0.1°C | -3.0°C | -6.1°C | 10.7°C | -17.6°C | 93 mm | 90% | 0.9 m/s | 1 |
| 2023 | 3.2°C | 0.2°C | -2.8°C | 9.9°C | -10.6°C | 133 mm | 90% | 0.7 m/s | 0.9 |
| 2022 | 0.8°C | -2.2°C | -5.1°C | 8.4°C | -12.3°C | 102 mm | 91% | 1 m/s | 1.1 |
| 2021 | 2.2°C | -1.0°C | -4.2°C | 13.5°C | -12.7°C | 73 mm | 85% | 0.9 m/s | 1.1 |
| 2020 | 1.1°C | -2.0°C | -5.1°C | 11.4°C | -13.4°C | 82 mm | 85% | 0.9 m/s | 0.9 |
| 2019 | -0.1°C | -3.6°C | -7.0°C | 5.7°C | -18.3°C | 76 mm | 90% | 0.9 m/s | 1 |
| 2018 | 0.4°C | -3.3°C | -6.9°C | 10.8°C | -13.4°C | 81 mm | 89% | 0.8 m/s | 1.1 |
| 2017 | -3.6°C | -6.7°C | -9.9°C | 9.6°C | -28.2°C | 83 mm | 91% | 0.9 m/s | 1.1 |
| 2016 | 0.2°C | -3.2°C | -6.5°C | 7.3°C | -21.4°C | 76 mm | 88% | 1 m/s | 1 |
| 2015 🔥 | 6.0°C | 2.9°C | -0.3°C | 16.9°C | -7.7°C | 93 mm | 88% | 0.9 m/s | 0.9 |
| 2014 | 0.4°C | -2.7°C | -5.9°C | 9.0°C | -11.7°C | 68 mm | 88% | 0.9 m/s | 1 |
| 2013 | -2.6°C | -5.9°C | -9.2°C | 7.7°C | -21.4°C | 93 mm | 93% | 0.8 m/s | 0.9 |
| 2012 | 0.9°C | -2.7°C | -6.4°C | 17.2°C | -16.8°C | 130 mm | 92% | 0.8 m/s | 1 |
| 2011 | 2.2°C | -1.5°C | -5.1°C | 8.9°C | -18.1°C | 88 mm | 87% | 0.8 m/s | 1.1 |
| 2010 | -3.3°C | -6.0°C | -8.8°C | 11.7°C | -17.0°C | 68 mm | 93% | 0.9 m/s | 1 |
| 2009 | -2.2°C | -5.5°C | -8.8°C | 10.6°C | -19.7°C | 95 mm | 92% | 0.9 m/s | 1.2 |
| 2008 | -1.4°C | -5.3°C | -9.3°C | 10.4°C | -19.6°C | 147 mm | 92% | 1.1 m/s | 1 |
| 2007 | -2.2°C | -5.7°C | -9.3°C | 2.6°C | -19.3°C | 127 mm | 96% | 0.9 m/s | 0.9 |
| 2006 | 2.9°C | -0.2°C | -3.2°C | 12.1°C | -12.9°C | 108 mm | 90% | 0.9 m/s | 1.1 |
| 2005 | -2.6°C | -5.7°C | -8.7°C | 3.1°C | -19.1°C | 80 mm | 95% | 0.9 m/s | 1.1 |
| 2004 | -1.0°C | -5.2°C | -9.5°C | 9.8°C | -25.9°C | 140 mm | 93% | 0.9 m/s | 0.9 |
| 2003 | -0.4°C | -3.8°C | -7.1°C | 7.1°C | -15.4°C | 98 mm | 89% | 0.9 m/s | 1.2 |
| 2002 | -1.4°C | -4.9°C | -8.4°C | 4.9°C | -18.7°C | 75 mm | 93% | 1 m/s | 1.3 |
| 2001 | 2.7°C | -0.2°C | -3.2°C | 15.3°C | -10.9°C | 79 mm | 91% | 0.9 m/s | 1.3 |
| 2000 | -4.1°C | -8.0°C | -11.9°C | 10.7°C | -19.4°C | 91 mm | 92% | 0.9 m/s | 1.2 |
| 1999 | 0.7°C | -2.8°C | -6.3°C | 14.5°C | -16.5°C | 62 mm | 86% | 1 m/s | 1 |
| 1998 | 3.5°C | -0.6°C | -4.6°C | 15.7°C | -19.8°C | 55 mm | 87% | 1 m/s | 1.2 |
| 1997 | -0.7°C | -4.1°C | -7.5°C | 3.4°C | -21.8°C | 71 mm | 92% | 0.9 m/s | 1.3 |
| 1996 | 0.8°C | -1.7°C | -4.2°C | 9.5°C | -20.1°C | 125 mm | 92% | 0.9 m/s | 1 |
| 1995 | -4.7°C | -8.0°C | -11.2°C | 2.5°C | -19.5°C | 71 mm | 96% | 0.8 m/s | 1.3 |
| 1994 | 1.0°C | -2.9°C | -6.7°C | 8.9°C | -20.1°C | 63 mm | 89% | 0.9 m/s | 1 |
| 1993 | -1.2°C | -5.3°C | -9.5°C | 4.0°C | -27.8°C | 96 mm | 93% | 0.9 m/s | 1 |
| 1992 | 0.0°C | -3.4°C | -6.9°C | 5.2°C | -17.2°C | 71 mm | 90% | 1 m/s | 1.1 |
| 1991 | -0.5°C | -4.5°C | -8.4°C | 8.8°C | -19.2°C | 87 mm | 89% | 0.9 m/s | 1.1 |
| 1990 | 0.9°C | -2.8°C | -6.4°C | 8.2°C | -14.4°C | 153 mm | 89% | 1 m/s | 1.1 |
| 1989 ❄️ | -8.3°C | -12.8°C | -17.3°C | 0.7°C | -29.9°C | 50 mm | 95% | 0.9 m/s | 1.4 |
| 1988 | -1.6°C | -5.3°C | -9.1°C | 6.4°C | -19.9°C | 55 mm | 86% | 1 m/s | 1 |
| 1987 | 0.1°C | -2.8°C | -5.7°C | 6.6°C | -18.2°C | 73 mm | 91% | 0.9 m/s | 1.1 |
| 1986 | -0.3°C | -3.8°C | -7.3°C | 2.6°C | -15.7°C | 92 mm | 93% | 0.9 m/s | 1.1 |
| 1985 | -3.3°C | -6.4°C | -9.6°C | 5.4°C | -20.3°C | 95 mm | 95% | 1 m/s | 1.1 |
| 1984 | 1.5°C | -1.9°C | -5.3°C | 12.3°C | -16.6°C | 130 mm | 89% | 1 m/s | 0.9 |
| 1983 🌧️ | -4.4°C | -8.3°C | -12.1°C | 1.5°C | -29.9°C | 181 mm | 98% | 1 m/s | — |
| 1982 | 2.8°C | -1.3°C | -5.4°C | 14.1°C | -18.6°C | 82 mm | 86% | 1 m/s | — |
| 1981 | -2.3°C | -5.0°C | -7.8°C | 5.3°C | -17.3°C | 51 mm | 94% | 0.8 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around -0.4°C with lows near -7.3°C (mean -3.8°C), based on 45 years of NASA POWER data.
December averages 92 mm of rainfall in Watertown, about average for rainfall. The wettest on record was 181 mm in 1983.
The hottest December reached 17.2°C in 2012. The coldest dipped to -29.9°C in 1983.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 2.1°C. Daytime highs moved from -1.1°C to 0.8°C and overnight lows from -8°C to -5.8°C over the same span.
December is one of the cooler months of the year in Watertown and about average for rainfall, so plan for around -0.4°C daytime highs and -7.3°C at night.
Not quite — December is the 3rd coolest month in Watertown, averaging -3.8°C.
For December in Watertown, pack warm layers and a jacket for chilly mornings, with typical highs of -0.4°C and lows of -7.3°C. Bring an umbrella or light rain jacket too.
Relative humidity in December averages 91% — quite humid.
Average wind speed in December is 0.9 m/s. The windiest December on record averaged 1.1 m/s (2008).
The wettest December on record was 1983 with 181 mm. On average, December sees 92 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 Watertown 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.
