December is one of the cooler months of the year in Saint John, with average highs near -0.5°C and lows around -8.5°C (mean -4.5°C). It is a relatively wet time of year, averaging 117 mm of rainfall and 90% relative humidity across the period.
December is one of the cooler months of the year in Saint John. Across 45 years of records, the warmest December in Saint John was 2015 — when the month averaged -0.7°C — while the coldest was 1989 at -15.1°C. Typical December days reach -0.5°C with nights near -8.5°C. The long-term trend is warming, about 0.7°C per decade.
December is a relatively wet time of year in Saint John, averaging 117 mm of rainfall. The wettest December on record was 2008 with 199 mm, while the driest was 1988 at 49 mm.
Relative humidity in Saint John during December averages 90%. The most humid December was 1997 at 99%, and the least humid was 1988 at 84%.
December receives about 1.2 kWh/m²/day of solar energy in Saint John. The sunniest December was 1989 at 1.5 kWh/m²/day, and the cloudiest were 1993 and 2013 at 0.9.
Average wind speed in Saint John during December is 0.5 m/s. The windiest Decembers were 2010, 2020 and 2022, among others at 0.6 m/s, while the calmest was 2001 at 0.4 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | -6.5°C | -4.6°C | -4.4°C | -4.0°C | -2.6°C | +3.9°C |
| Avg High | -2.1°C | -0.5°C | -0.5°C | -0.2°C | 1.2°C | +3.3°C |
| Avg Low | -10.9°C | -8.6°C | -8.3°C | -7.8°C | -6.5°C | +4.4°C |
| Avg Rain | 99 mm | 111 mm | 114 mm | 141 mm | 122 mm | +22 mm |
December temperatures in Saint John have risen by about 2°C between 1981–1985 and 2021–2025.
December has ranged from a record low of -33.6°C (1989) to a record high of 14.7°C (2020).
Rainfall in December is a relatively wet time of year, averaging 117 mm, with a wettest year of 199 mm.
Daytime highs and overnight lows have shifted differently — highs rose about 0.5°C per decade while lows rose 0.8°C per decade, narrowing the gap between day and night.
A quieter season to visit Saint John
If your dates are flexible, the more temperate months of July and August tend to be the most comfortable for visiting Saint John. That said, December — with days averaging -0.5°C and nights around -8.5°C (mean -4.5°C) and higher rainfall (117 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 | -1.8°C | -6.2°C | -10.5°C | 12.5°C | -19.7°C | 94 mm | 85% | 0.5 m/s | — |
| 2024 | 0.5°C | -3.3°C | -7.1°C | 12.7°C | -16.9°C | 100 mm | 89% | 0.5 m/s | 1.3 |
| 2023 | 2.4°C | -1.2°C | -4.8°C | 14.6°C | -12.4°C | 114 mm | 90% | 0.5 m/s | 1.2 |
| 2022 | 2.0°C | -1.5°C | -5.1°C | 11.1°C | -11.9°C | 145 mm | 89% | 0.6 m/s | 1.1 |
| 2021 | 1.7°C | -2.6°C | -6.9°C | 12.2°C | -16.1°C | 83 mm | 85% | 0.5 m/s | 1.2 |
| 2020 | 2.5°C | -1.1°C | -4.6°C | 14.7°C | -18.0°C | 193 mm | 90% | 0.6 m/s | 1.1 |
| 2019 | 0.4°C | -3.7°C | -7.7°C | 11.5°C | -16.3°C | 126 mm | 88% | 0.5 m/s | 1.2 |
| 2018 | -2.1°C | -6.2°C | -10.3°C | 11.1°C | -18.5°C | 112 mm | 90% | 0.5 m/s | 1.4 |
| 2017 | -3.0°C | -7.0°C | -11.0°C | 10.0°C | -27.6°C | 114 mm | 90% | 0.5 m/s | 1.2 |
| 2016 | -1.7°C | -5.8°C | -9.9°C | 8.6°C | -26.4°C | 112 mm | 91% | 0.5 m/s | 1.2 |
| 2015 🔥 | 2.2°C | -0.7°C | -3.6°C | 9.3°C | -14.5°C | 155 mm | 94% | 0.5 m/s | 1.1 |
| 2014 | 1.5°C | -2.0°C | -5.6°C | 11.7°C | -18.3°C | 189 mm | 88% | 0.5 m/s | 1.1 |
| 2013 | -3.6°C | -7.4°C | -11.1°C | 5.8°C | -23.9°C | 135 mm | 93% | 0.5 m/s | 0.9 |
| 2012 | 0.5°C | -3.4°C | -7.3°C | 9.9°C | -15.9°C | 150 mm | 91% | 0.5 m/s | 1.2 |
| 2011 | 2.5°C | -1.8°C | -6.0°C | 10.7°C | -15.8°C | 124 mm | 88% | 0.5 m/s | 1.2 |
| 2010 | 1.0°C | -2.1°C | -5.2°C | 14.1°C | -14.1°C | 197 mm | 93% | 0.6 m/s | 1 |
| 2009 | -1.4°C | -4.6°C | -7.9°C | 13.2°C | -17.4°C | 122 mm | 93% | 0.6 m/s | 1.1 |
| 2008 🌧️ | 1.0°C | -3.6°C | -8.2°C | 11.3°C | -18.9°C | 199 mm | 87% | 0.6 m/s | 1.1 |
| 2007 | -2.4°C | -7.1°C | -11.8°C | 8.2°C | -21.3°C | 107 mm | 94% | 0.6 m/s | 1.2 |
| 2006 | 1.4°C | -2.2°C | -5.9°C | 10.8°C | -15.3°C | 91 mm | 88% | 0.5 m/s | 1.2 |
| 2005 | -0.7°C | -4.0°C | -7.4°C | 9.7°C | -17.1°C | 121 mm | 89% | 0.5 m/s | 1.2 |
| 2004 | -1.1°C | -5.6°C | -10.0°C | 9.8°C | -19.6°C | 103 mm | 86% | 0.5 m/s | 1.1 |
| 2003 | 0.6°C | -3.1°C | -6.7°C | 9.9°C | -14.7°C | 118 mm | 86% | 0.6 m/s | 1.2 |
| 2002 | -1.5°C | -5.6°C | -9.8°C | 8.9°C | -18.9°C | 115 mm | 89% | 0.5 m/s | 1.4 |
| 2001 | 1.7°C | -1.5°C | -4.7°C | 12.6°C | -10.4°C | 55 mm | 88% | 0.4 m/s | 1.3 |
| 2000 | -2.2°C | -6.5°C | -10.8°C | 12.0°C | -19.4°C | 109 mm | 87% | 0.5 m/s | 1.3 |
| 1999 | 0.6°C | -2.9°C | -6.3°C | 10.3°C | -15.6°C | 109 mm | 87% | 0.5 m/s | 1.1 |
| 1998 | 1.2°C | -3.1°C | -7.4°C | 12.1°C | -19.6°C | 62 mm | 86% | 0.5 m/s | 1.2 |
| 1997 | -2.7°C | -7.7°C | -12.8°C | 1.8°C | -24.0°C | 87 mm | 99% | 0.5 m/s | 1.2 |
| 1996 | 2.1°C | -1.4°C | -4.8°C | 9.8°C | -22.2°C | 147 mm | 89% | 0.5 m/s | 1.2 |
| 1995 | -3.2°C | -6.9°C | -10.6°C | 3.8°C | -18.0°C | 79 mm | 91% | 0.5 m/s | 1.4 |
| 1994 | -1.1°C | -5.1°C | -9.1°C | 6.3°C | -18.0°C | 85 mm | 91% | 0.5 m/s | 1.1 |
| 1993 | -0.4°C | -4.0°C | -7.6°C | 13.2°C | -28.3°C | 170 mm | 88% | 0.6 m/s | 0.9 |
| 1992 | -0.6°C | -4.4°C | -8.2°C | 6.7°C | -19.0°C | 92 mm | 90% | 0.5 m/s | 1.1 |
| 1991 | -2.6°C | -7.4°C | -12.3°C | 9.5°C | -22.8°C | 74 mm | 91% | 0.5 m/s | 1.2 |
| 1990 | 1.6°C | -2.9°C | -7.4°C | 12.2°C | -16.9°C | 199 mm | 88% | 0.5 m/s | 1.1 |
| 1989 ❄️ | -10.0°C | -15.1°C | -20.2°C | 0.3°C | -33.6°C | 70 mm | 99% | 0.5 m/s | 1.5 |
| 1988 | -2.2°C | -6.2°C | -10.3°C | 5.7°C | -20.6°C | 49 mm | 84% | 0.5 m/s | 1.2 |
| 1987 | -2.7°C | -6.5°C | -10.3°C | 8.2°C | -23.2°C | 118 mm | 95% | 0.5 m/s | 1.2 |
| 1986 | -0.7°C | -5.6°C | -10.4°C | 9.9°C | -21.2°C | 69 mm | 87% | 0.5 m/s | 1.2 |
| 1985 | -3.2°C | -8.0°C | -12.8°C | 10.0°C | -24.6°C | 78 mm | 90% | 0.5 m/s | 1.2 |
| 1984 | 0.3°C | -4.3°C | -8.9°C | 6.7°C | -24.0°C | 103 mm | 88% | 0.5 m/s | 1.1 |
| 1983 | -1.7°C | -6.0°C | -10.4°C | 9.0°C | -23.6°C | 142 mm | 86% | 0.5 m/s | — |
| 1982 | 1.3°C | -3.1°C | -7.6°C | 12.1°C | -21.0°C | 79 mm | 87% | 0.5 m/s | — |
| 1981 | -0.2°C | -3.6°C | -7.0°C | 8.5°C | -20.1°C | 183 mm | 95% | 0.5 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around -0.5°C with lows near -8.5°C (mean -4.5°C), based on 45 years of NASA POWER data.
December averages 117 mm of rainfall in Saint John, a relatively wet time of year. The wettest on record was 199 mm in 2008.
The hottest December reached 14.7°C in 2020. The coldest dipped to -33.6°C in 1989.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 2°C. Daytime highs moved from -0.7°C to 1°C and overnight lows from -9.3°C to -6.9°C over the same span.
December is one of the cooler months of the year in Saint John and a relatively wet time of year, so plan for around -0.5°C daytime highs and -8.5°C at night.
Not quite — December is the 3rd coolest month in Saint John, averaging -4.5°C.
For December in Saint John, pack warm layers and a jacket for chilly mornings, with typical highs of -0.5°C and lows of -8.5°C. Bring an umbrella or light rain jacket too.
Relative humidity in December averages 90% — quite humid.
Average wind speed in December is 0.5 m/s. The windiest December on record averaged 0.6 m/s (1993).
The wettest December on record was 2008 with 199 mm. On average, December sees 117 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 Saint John 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.
