December is one of the cooler months of the year in Summerside, with average highs near 0°C and lows around -5.2°C (mean -2.6°C). It is about average for rainfall, averaging 95 mm of rainfall and 87% relative humidity across the period.
December is one of the cooler months of the year in Summerside. Across 45 years of records, the warmest December in Summerside was 2010 — when the month averaged 1.1°C — while the coldest was 1989 at -10.9°C. Typical December days reach 0°C with nights near -5.2°C. The long-term trend is warming, about 0.6°C per decade.
December is about average for rainfall in Summerside, averaging 95 mm of rainfall. The wettest December on record was 1990 with 194 mm, while the driest was 1986 at 39 mm.
Relative humidity in Summerside during December averages 87%. The most humid December was 1989 at 97%, and the least humid was 2025 at 82%.
December receives about 0.9 kWh/m²/day of solar energy in Summerside. The sunniest Decembers were 2021, 2023 and 2024, among others at 1 kWh/m²/day, and the cloudiest were 1993 and 2013 at 0.7.
Average wind speed in Summerside during December is 5 m/s. The windiest Decembers were 2000 and 2010 at 5.7 m/s, while the calmest was 2015 at 4.2 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | -4.4°C | -2.4°C | -2.6°C | -2.1°C | -1.0°C | +3.4°C |
| Avg High | -1.4°C | 0.2°C | -0.1°C | 0.3°C | 1.7°C | +3.1°C |
| Avg Low | -7.4°C | -5.0°C | -5.2°C | -4.5°C | -3.5°C | +3.9°C |
| Avg Rain | 89 mm | 78 mm | 106 mm | 115 mm | 82 mm | -7 mm |
December temperatures in Summerside have risen by about 1.8°C between 1981–1985 and 2021–2025.
December has ranged from a record low of -23.5°C (1989) to a record high of 13.8°C (2011).
Rainfall in December is about average for rainfall, averaging 95 mm, with a wettest year of 194 mm.
A quieter season to visit Summerside
If your dates are flexible, the more temperate months of August and July tend to be the most comfortable for visiting Summerside. That said, December — with days averaging 0°C and nights around -5.2°C (mean -2.6°C) and higher rainfall (95 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 | -0.6°C | -3.6°C | -6.5°C | 11.8°C | -11.2°C | 69 mm | 82% | 5.5 m/s | — |
| 2024 | 1.0°C | -1.6°C | -4.1°C | 12.4°C | -10.9°C | 69 mm | 86% | 4.3 m/s | 1 |
| 2023 | 2.7°C | 0.3°C | -2.0°C | 13.1°C | -6.7°C | 66 mm | 86% | 4.8 m/s | 1 |
| 2022 | 2.0°C | -0.2°C | -2.4°C | 10.3°C | -9.9°C | 109 mm | 87% | 4.7 m/s | 0.9 |
| 2021 | 1.8°C | -1.2°C | -4.1°C | 12.2°C | -12.0°C | 69 mm | 83% | 4.8 m/s | 1 |
| 2020 | 3.0°C | 0.5°C | -2.1°C | 13.2°C | -9.8°C | 112 mm | 88% | 4.8 m/s | 0.9 |
| 2019 | 0.2°C | -2.3°C | -4.9°C | 10.6°C | -9.8°C | 82 mm | 85% | 5.1 m/s | 0.9 |
| 2018 | -2.3°C | -4.8°C | -7.2°C | 9.1°C | -12.9°C | 78 mm | 89% | 4.5 m/s | 0.9 |
| 2017 | -1.6°C | -4.4°C | -7.1°C | 10.1°C | -17.3°C | 94 mm | 88% | 5 m/s | 0.9 |
| 2016 | -0.8°C | -3.4°C | -6.0°C | 5.7°C | -17.0°C | 111 mm | 89% | 5.1 m/s | 0.8 |
| 2015 | 1.7°C | -0.2°C | -2.1°C | 7.5°C | -10.3°C | 143 mm | 90% | 4.2 m/s | 0.8 |
| 2014 | 1.9°C | -0.7°C | -3.3°C | 11.4°C | -13.5°C | 183 mm | 85% | 4.4 m/s | 0.8 |
| 2013 | -2.6°C | -5.4°C | -8.1°C | 4.0°C | -16.0°C | 150 mm | 90% | 4.9 m/s | 0.7 |
| 2012 | 1.3°C | -0.8°C | -3.0°C | 8.1°C | -8.4°C | 98 mm | 88% | 5.1 m/s | 0.8 |
| 2011 | 2.6°C | -0.2°C | -3.0°C | 13.8°C | -9.3°C | 98 mm | 85% | 4.6 m/s | 0.9 |
| 2010 🔥 | 3.0°C | 1.1°C | -0.7°C | 11.5°C | -5.3°C | 115 mm | 89% | 5.7 m/s | 0.8 |
| 2009 | -0.1°C | -2.3°C | -4.4°C | 8.6°C | -13.0°C | 93 mm | 89% | 5.2 m/s | 0.8 |
| 2008 | 1.8°C | -1.7°C | -5.3°C | 12.4°C | -11.6°C | 156 mm | 86% | 5.3 m/s | 0.8 |
| 2007 | -2.1°C | -4.8°C | -7.5°C | 6.1°C | -14.3°C | 102 mm | 89% | 5.2 m/s | 0.8 |
| 2006 | 0.1°C | -2.5°C | -5.1°C | 9.8°C | -12.3°C | 86 mm | 89% | 4.8 m/s | 0.9 |
| 2005 | -0.1°C | -2.3°C | -4.6°C | 9.1°C | -10.8°C | 106 mm | 88% | 5.2 m/s | 0.8 |
| 2004 | -0.8°C | -3.9°C | -6.9°C | 9.1°C | -14.2°C | 129 mm | 88% | 5.1 m/s | 0.8 |
| 2003 | 0.8°C | -1.5°C | -3.9°C | 9.4°C | -9.1°C | 127 mm | 86% | 5.4 m/s | 0.9 |
| 2002 | -1.1°C | -3.3°C | -5.5°C | 6.0°C | -16.0°C | 93 mm | 88% | 5.1 m/s | 0.9 |
| 2001 | 1.7°C | -0.3°C | -2.2°C | 10.5°C | -6.4°C | 54 mm | 83% | 4.6 m/s | 1 |
| 2000 | -0.9°C | -3.9°C | -6.9°C | 10.6°C | -13.9°C | 113 mm | 86% | 5.7 m/s | 1 |
| 1999 | 1.3°C | -1.2°C | -3.6°C | 10.6°C | -12.7°C | 73 mm | 86% | 5 m/s | 0.8 |
| 1998 | 0.6°C | -2.2°C | -4.9°C | 9.1°C | -16.3°C | 44 mm | 83% | 5.2 m/s | 0.9 |
| 1997 | -0.6°C | -3.0°C | -5.5°C | 4.5°C | -13.2°C | 58 mm | 87% | 4.8 m/s | 0.9 |
| 1996 | 2.4°C | -0.3°C | -3.1°C | 10.8°C | -17.4°C | 98 mm | 88% | 4.9 m/s | 0.9 |
| 1995 | -1.3°C | -3.3°C | -5.3°C | 4.7°C | -11.7°C | 64 mm | 84% | 5.3 m/s | 0.9 |
| 1994 | -0.3°C | -2.8°C | -5.3°C | 4.2°C | -11.2°C | 69 mm | 86% | 4.9 m/s | 0.8 |
| 1993 | 0.2°C | -2.3°C | -4.7°C | 10.9°C | -20.3°C | 70 mm | 86% | 5.3 m/s | 0.7 |
| 1992 | -0.2°C | -2.7°C | -5.3°C | 6.7°C | -15.5°C | 59 mm | 86% | 5 m/s | 0.8 |
| 1991 | -1.1°C | -4.2°C | -7.3°C | 9.8°C | -13.3°C | 49 mm | 87% | 5.1 m/s | 0.8 |
| 1990 🌧️ | 1.0°C | -2.2°C | -5.4°C | 12.0°C | -14.2°C | 194 mm | 88% | 4.9 m/s | 0.8 |
| 1989 ❄️ | -7.3°C | -10.9°C | -14.4°C | 0.8°C | -23.5°C | 58 mm | 97% | 5.5 m/s | 0.9 |
| 1988 | -1.7°C | -4.7°C | -7.6°C | 5.7°C | -16.1°C | 55 mm | 87% | 4.9 m/s | 0.9 |
| 1987 | -1.9°C | -4.4°C | -6.9°C | 9.7°C | -15.0°C | 139 mm | 91% | 4.9 m/s | 0.8 |
| 1986 | -0.7°C | -4.0°C | -7.3°C | 8.4°C | -16.7°C | 39 mm | 87% | 4.9 m/s | 0.9 |
| 1985 | -2.3°C | -5.7°C | -9.2°C | 8.6°C | -15.2°C | 58 mm | 86% | 4.9 m/s | 0.9 |
| 1984 | 0.4°C | -3.0°C | -6.4°C | 6.7°C | -19.4°C | 78 mm | 87% | 4.9 m/s | 0.9 |
| 1983 | -1.1°C | -4.0°C | -6.9°C | 9.5°C | -16.8°C | 133 mm | 88% | 5.4 m/s | — |
| 1982 | 1.0°C | -2.0°C | -5.0°C | 11.7°C | -15.6°C | 94 mm | 87% | 4.9 m/s | — |
| 1981 | 1.1°C | -0.9°C | -3.0°C | 8.6°C | -11.2°C | 149 mm | 90% | 4.5 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around 0°C with lows near -5.2°C (mean -2.6°C), based on 45 years of NASA POWER data.
December averages 95 mm of rainfall in Summerside, about average for rainfall. The wettest on record was 194 mm in 1990.
The hottest December reached 13.8°C in 2011. The coldest dipped to -23.5°C in 1989.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 1.8°C. Daytime highs moved from -0.2°C to 1.4°C and overnight lows from -6.1°C to -3.8°C over the same span.
December is one of the cooler months of the year in Summerside and about average for rainfall, so plan for around 0°C daytime highs and -5.2°C at night.
Not quite — December is the 4th coolest month in Summerside, averaging -2.6°C.
For December in Summerside, pack warm layers and a jacket for chilly mornings, with typical highs of 0°C and lows of -5.2°C. Bring an umbrella or light rain jacket too.
Relative humidity in December averages 87% — quite humid.
Average wind speed in December is 5 m/s. The windiest December on record averaged 5.7 m/s (2000).
The wettest December on record was 1990 with 194 mm. On average, December sees 95 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 Summerside 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.
