December is one of the cooler months of the year in St. Catharines, with average highs near 2.3°C and lows around -2.5°C (mean -0.1°C). It is about average for rainfall, averaging 62 mm of rainfall and 84% relative humidity across the period.
December is one of the cooler months of the year in St. Catharines. Across 45 years of records, the warmest December in St. Catharines was 2015 — when the month averaged 5.3°C — while the coldest was 1989 at -6.5°C. Typical December days reach 2.3°C with nights near -2.5°C. The long-term trend is warming, about 0.6°C per decade.
December is about average for rainfall in St. Catharines, averaging 62 mm of rainfall. The wettest December on record was 1983 with 118 mm, while the driest was 1995 at 26 mm.
Relative humidity in St. Catharines during December averages 84%. The most humid December was 1983 at 90%, and the least humid was 2025 at 80%.
December receives about 1.1 kWh/m²/day of solar energy in St. Catharines. The sunniest December was 1995 at 1.4 kWh/m²/day, and the cloudiest was 1984 at 0.9.
Average wind speed in St. Catharines during December is 4.7 m/s. The windiest December was 2008 at 5.8 m/s, while the calmest were 1994 and 2023 at 3.5 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | -1.3°C | -0.1°C | -0.5°C | 0.6°C | 1.3°C | +2.6°C |
| Avg High | 1.0°C | 2.5°C | 1.8°C | 2.9°C | 3.7°C | +2.7°C |
| Avg Low | -3.7°C | -2.7°C | -2.9°C | -1.7°C | -1.1°C | +2.6°C |
| Avg Rain | 63 mm | 45 mm | 80 mm | 63 mm | 60 mm | -3 mm |
December temperatures in St. Catharines have risen by about 2.2°C between 1981–1985 and 2021–2025.
December has ranged from a record low of -14.8°C (1983) to a record high of 16.3°C (1982).
Rainfall in December is about average for rainfall, averaging 62 mm, with a wettest year of 118 mm.
A quieter season to visit St. Catharines
If your dates are flexible, the more temperate months of July and August tend to be the most comfortable for visiting St. Catharines. That said, December — with days averaging 2.3°C and nights around -2.5°C (mean -0.1°C) and moderate rainfall (62 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 | 1.3°C | -1.6°C | -4.6°C | 10.3°C | -8.5°C | 64 mm | 80% | 5.5 m/s | — |
| 2024 | 3.2°C | 0.8°C | -1.5°C | 11.8°C | -10.5°C | 69 mm | 83% | 4.5 m/s | 1.1 |
| 2023 | 5.9°C | 3.8°C | 1.7°C | 12.6°C | -2.3°C | 70 mm | 85% | 3.5 m/s | 1 |
| 2022 | 2.8°C | 0.6°C | -1.6°C | 9.8°C | -11.7°C | 62 mm | 83% | 5.1 m/s | 1.1 |
| 2021 | 5.5°C | 2.7°C | -0.1°C | 14.6°C | -3.4°C | 44 mm | 80% | 4.6 m/s | 1.2 |
| 2020 | 3.5°C | 1.4°C | -0.8°C | 10.9°C | -3.5°C | 51 mm | 82% | 4.9 m/s | 1.2 |
| 2019 | 3.3°C | 0.7°C | -1.9°C | 9.0°C | -11.2°C | 83 mm | 86% | 4.4 m/s | 1.1 |
| 2018 | 3.1°C | 1.0°C | -1.1°C | 11.2°C | -4.8°C | 56 mm | 86% | 3.7 m/s | 1.1 |
| 2017 | -0.2°C | -2.2°C | -4.3°C | 10.2°C | -14.6°C | 50 mm | 84% | 4.9 m/s | 1.3 |
| 2016 | 2.3°C | 0.1°C | -2.1°C | 10.2°C | -9.4°C | 71 mm | 83% | 5.7 m/s | 1.1 |
| 2015 🔥 | 8.0°C | 5.3°C | 2.6°C | 15.6°C | -2.3°C | 56 mm | 86% | 4.2 m/s | 1.1 |
| 2014 | 3.2°C | 1.0°C | -1.2°C | 10.5°C | -7.5°C | 42 mm | 82% | 4.2 m/s | 1.2 |
| 2013 | 0.5°C | -1.8°C | -4.1°C | 11.5°C | -11.4°C | 76 mm | 85% | 4.6 m/s | 1.1 |
| 2012 | 4.7°C | 2.4°C | 0.0°C | 13.3°C | -4.5°C | 75 mm | 86% | 4.2 m/s | 1.1 |
| 2011 | 4.4°C | 1.9°C | -0.6°C | 11.1°C | -7.7°C | 73 mm | 85% | 4.1 m/s | 1.3 |
| 2010 | -0.7°C | -2.5°C | -4.2°C | 6.4°C | -9.5°C | 46 mm | 87% | 5.1 m/s | 1.1 |
| 2009 | 1.5°C | -0.6°C | -2.6°C | 9.1°C | -10.2°C | 73 mm | 83% | 4.9 m/s | 1.3 |
| 2008 | 1.9°C | -1.0°C | -3.9°C | 12.2°C | -10.7°C | 112 mm | 83% | 5.8 m/s | 1.1 |
| 2007 | 1.4°C | -0.7°C | -2.9°C | 7.3°C | -7.5°C | 108 mm | 87% | 4.6 m/s | 1 |
| 2006 | 5.1°C | 2.7°C | 0.4°C | 10.1°C | -7.7°C | 82 mm | 86% | 5.1 m/s | 1.3 |
| 2005 | -0.1°C | -1.8°C | -3.5°C | 4.3°C | -9.4°C | 49 mm | 86% | 4.7 m/s | 1.1 |
| 2004 | 2.7°C | -0.1°C | -3.0°C | 13.3°C | -14.2°C | 100 mm | 86% | 5.2 m/s | 1.2 |
| 2003 | 2.4°C | 0.0°C | -2.3°C | 7.7°C | -7.3°C | 67 mm | 85% | 4.3 m/s | 1.3 |
| 2002 | 0.6°C | -1.9°C | -4.5°C | 5.4°C | -13.2°C | 66 mm | 87% | 4.7 m/s | 1.1 |
| 2001 | 4.1°C | 1.8°C | -0.5°C | 14.7°C | -6.1°C | 72 mm | 87% | 4.4 m/s | 1.3 |
| 2000 | -1.6°C | -3.9°C | -6.3°C | 4.6°C | -12.0°C | 74 mm | 87% | 4.9 m/s | 1.3 |
| 1999 | 3.1°C | 0.6°C | -2.0°C | 14.1°C | -9.5°C | 57 mm | 82% | 4.8 m/s | 1.1 |
| 1998 | 5.6°C | 2.6°C | -0.4°C | 15.6°C | -10.6°C | 47 mm | 81% | 4.8 m/s | 1.3 |
| 1997 | 2.8°C | 0.6°C | -1.5°C | 6.8°C | -9.6°C | 42 mm | 83% | 4.6 m/s | 1.2 |
| 1996 | 2.9°C | 0.4°C | -2.0°C | 9.7°C | -9.4°C | 41 mm | 86% | 4.2 m/s | 1 |
| 1995 | -1.1°C | -3.4°C | -5.6°C | 7.2°C | -10.5°C | 26 mm | 83% | 4.9 m/s | 1.4 |
| 1994 | 3.4°C | 0.7°C | -2.1°C | 11.5°C | -10.0°C | 33 mm | 86% | 3.5 m/s | 1 |
| 1993 | 0.7°C | -1.7°C | -4.0°C | 7.7°C | -13.5°C | 34 mm | 84% | 4.3 m/s | 1.1 |
| 1992 | 1.8°C | -0.5°C | -2.8°C | 7.3°C | -9.6°C | 46 mm | 85% | 4.5 m/s | 1 |
| 1991 | 2.4°C | -0.6°C | -3.6°C | 10.0°C | -11.9°C | 40 mm | 83% | 4.7 m/s | 1.1 |
| 1990 | 3.1°C | -0.1°C | -3.4°C | 9.6°C | -12.5°C | 81 mm | 84% | 4.7 m/s | 1.1 |
| 1989 ❄️ | -4.3°C | -6.5°C | -8.7°C | 3.7°C | -13.8°C | 31 mm | 84% | 4.2 m/s | 1.2 |
| 1988 | 1.0°C | -1.7°C | -4.4°C | 8.2°C | -13.3°C | 36 mm | 80% | 5.2 m/s | 1.1 |
| 1987 | 2.8°C | 0.3°C | -2.1°C | 9.5°C | -11.0°C | 45 mm | 84% | 4.8 m/s | 1.1 |
| 1986 | 2.0°C | 0.1°C | -1.8°C | 4.6°C | -9.2°C | 69 mm | 86% | 4.6 m/s | 1.1 |
| 1985 | -0.6°C | -2.6°C | -4.6°C | 9.5°C | -10.7°C | 49 mm | 86% | 5.7 m/s | 1 |
| 1984 | 4.2°C | 1.3°C | -1.6°C | 12.5°C | -8.3°C | 92 mm | 84% | 5.2 m/s | 0.9 |
| 1983 🌧️ | -2.0°C | -4.1°C | -6.2°C | 4.5°C | -14.8°C | 118 mm | 90% | 5.6 m/s | — |
| 1982 | 5.1°C | 2.1°C | -0.8°C | 16.3°C | -8.7°C | 92 mm | 85% | 4.5 m/s | — |
| 1981 | 1.0°C | -1.0°C | -3.1°C | 5.5°C | -9.1°C | 37 mm | 84% | 4.5 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around 2.3°C with lows near -2.5°C (mean -0.1°C), based on 45 years of NASA POWER data.
December averages 62 mm of rainfall in St. Catharines, about average for rainfall. The wettest on record was 118 mm in 1983.
The hottest December reached 16.3°C in 1982. The coldest dipped to -14.8°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 1.5°C to 3.7°C and overnight lows from -3.3°C to -1.2°C over the same span.
December is one of the cooler months of the year in St. Catharines and about average for rainfall, so plan for around 2.3°C daytime highs and -2.5°C at night.
Not quite — December is the 3rd coolest month in St. Catharines, averaging -0.1°C.
For December in St. Catharines, pack warm layers and a jacket for chilly mornings, with typical highs of 2.3°C and lows of -2.5°C. Bring an umbrella or light rain jacket too.
Relative humidity in December averages 84% — quite humid.
Average wind speed in December is 4.7 m/s. The windiest December on record averaged 5.8 m/s (2008).
The wettest December on record was 1983 with 118 mm. On average, December sees 62 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 St. Catharines 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.
