December is one of the cooler months of the year in Belfast, with average highs near 7.9°C and lows around 5.1°C (mean 6.5°C). It is a relatively wet time of year, averaging 107 mm of rainfall and 90% relative humidity across the period.
December is one of the cooler months of the year in Belfast. Across 45 years of records, the warmest December in Belfast was 2015 — when the month averaged 8.3°C — while the coldest was 2010 at 3.4°C. Typical December days reach 7.9°C with nights near 5.1°C. The long-term trend is warming, about 0.2°C per decade.
December is a relatively wet time of year in Belfast, averaging 107 mm of rainfall. The wettest December on record was 2015 with 198 mm, while the driest was 2010 at 46 mm.
Relative humidity in Belfast during December averages 90%. The most humid Decembers were 2018 and 2019 at 93%, and the least humid was 1995 at 85%.
December receives about 0.4 kWh/m²/day of solar energy in Belfast. The sunniest Decembers were 2010, 2020 and 2022, among others at 0.5 kWh/m²/day, and the cloudiest was 2021 at 0.3.
Average wind speed in Belfast during December is 5.8 m/s. The windiest December was 2013 at 7.4 m/s, while the calmest was 2010 at 4.1 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 6.3°C | 6.1°C | 6.7°C | 6.5°C | 7.2°C | +0.9°C |
| Avg High | 7.7°C | 7.6°C | 8.1°C | 8.1°C | 8.5°C | +0.8°C |
| Avg Low | 4.9°C | 4.7°C | 5.3°C | 5.0°C | 5.8°C | +0.9°C |
| Avg Rain | 101 mm | 103 mm | 105 mm | 109 mm | 122 mm | +21 mm |
December temperatures in Belfast have risen by about 1.3°C between 1981–1985 and 2021–2025.
December has ranged from a record low of -1.5°C (1981) to a record high of 13.3°C (1994).
Rainfall in December is a relatively wet time of year, averaging 107 mm, with a wettest year of 198 mm.
A quieter season to visit Belfast
If your dates are flexible, the more temperate months of July and August tend to be the most comfortable for visiting Belfast. That said, December — with days averaging 7.9°C and nights around 5.1°C (mean 6.5°C) and higher rainfall (107 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 | 8.9°C | 7.6°C | 6.2°C | 13.2°C | 2.2°C | 129 mm | 91% | 5.6 m/s | — |
| 2024 | 9.4°C | 7.8°C | 6.2°C | 12.3°C | 3.4°C | 104 mm | 91% | 6.1 m/s | 0.4 |
| 2023 | 9.2°C | 7.9°C | 6.7°C | 11.8°C | 2.8°C | 158 mm | 91% | 6.5 m/s | 0.4 |
| 2022 | 7.1°C | 5.8°C | 4.5°C | 12.4°C | 2.3°C | 92 mm | 90% | 5.1 m/s | 0.5 |
| 2021 | 8.7°C | 7.3°C | 5.9°C | 11.9°C | 3.1°C | 136 mm | 92% | 5.4 m/s | 0.3 |
| 2020 | 7.7°C | 6.5°C | 5.3°C | 11.6°C | 2.8°C | 114 mm | 91% | 5.8 m/s | 0.5 |
| 2019 | 8.2°C | 6.7°C | 5.2°C | 12.4°C | 2.0°C | 96 mm | 93% | 6 m/s | 0.4 |
| 2018 | 9.0°C | 7.7°C | 6.3°C | 11.6°C | 3.3°C | 115 mm | 93% | 5.5 m/s | 0.4 |
| 2017 | 7.6°C | 6.2°C | 4.8°C | 12.2°C | 1.1°C | 97 mm | 92% | 5.5 m/s | 0.4 |
| 2016 | 9.2°C | 7.7°C | 6.3°C | 12.8°C | 3.5°C | 73 mm | 92% | 5.4 m/s | 0.4 |
| 2015 🔥 🌧️ | 10.4°C | 8.3°C | 6.2°C | 12.6°C | 3.0°C | 198 mm | 92% | 7.2 m/s | 0.4 |
| 2014 | 7.5°C | 6.1°C | 4.7°C | 11.5°C | 1.5°C | 100 mm | 92% | 6.1 m/s | 0.4 |
| 2013 | 8.8°C | 7.0°C | 5.3°C | 12.0°C | 2.4°C | 101 mm | 91% | 7.4 m/s | 0.4 |
| 2012 | 7.5°C | 6.0°C | 4.5°C | 11.1°C | 2.9°C | 149 mm | 91% | 5.7 m/s | 0.4 |
| 2011 | 7.8°C | 6.3°C | 4.7°C | 11.9°C | 1.1°C | 114 mm | 92% | 7.2 m/s | 0.4 |
| 2010 ❄️ | 4.6°C | 3.4°C | 2.1°C | 9.2°C | -0.6°C | 46 mm | 88% | 4.1 m/s | 0.5 |
| 2009 | 6.5°C | 5.1°C | 3.8°C | 11.3°C | 1.1°C | 84 mm | 90% | 5.1 m/s | 0.5 |
| 2008 | 7.2°C | 5.7°C | 4.2°C | 11.3°C | 2.1°C | 82 mm | 90% | 4.9 m/s | 0.4 |
| 2007 | 8.9°C | 7.2°C | 5.5°C | 13.1°C | 3.2°C | 106 mm | 91% | 6.2 m/s | 0.4 |
| 2006 | 9.2°C | 7.6°C | 5.9°C | 12.4°C | 3.7°C | 128 mm | 92% | 6.3 m/s | 0.4 |
| 2005 | 8.5°C | 7.2°C | 5.9°C | 11.4°C | 2.3°C | 104 mm | 90% | 5 m/s | 0.4 |
| 2004 | 8.7°C | 7.3°C | 5.8°C | 11.3°C | 2.1°C | 81 mm | 92% | 6 m/s | 0.4 |
| 2003 | 8.5°C | 7.0°C | 5.6°C | 11.5°C | 1.9°C | 111 mm | 89% | 5.4 m/s | 0.4 |
| 2002 | 7.7°C | 6.9°C | 6.0°C | 11.4°C | 3.2°C | 100 mm | 89% | 5.6 m/s | 0.4 |
| 2001 | 7.7°C | 6.2°C | 4.6°C | 12.0°C | 1.2°C | 72 mm | 89% | 5.4 m/s | 0.5 |
| 2000 | 7.7°C | 6.6°C | 5.4°C | 11.7°C | -0.4°C | 185 mm | 91% | 6 m/s | 0.4 |
| 1999 | 7.4°C | 5.9°C | 4.3°C | 11.6°C | 1.6°C | 164 mm | 90% | 7 m/s | 0.4 |
| 1998 | 8.6°C | 6.8°C | 5.1°C | 12.1°C | 1.6°C | 105 mm | 91% | 6.1 m/s | 0.4 |
| 1997 | 8.6°C | 7.3°C | 6.1°C | 12.3°C | 3.3°C | 130 mm | 91% | 6.2 m/s | 0.4 |
| 1996 | 6.4°C | 5.2°C | 4.0°C | 10.0°C | 1.1°C | 60 mm | 88% | 5.3 m/s | 0.4 |
| 1995 | 6.3°C | 5.2°C | 4.1°C | 12.4°C | 0.5°C | 66 mm | 85% | 5.4 m/s | 0.4 |
| 1994 | 8.8°C | 7.2°C | 5.7°C | 13.3°C | 2.1°C | 121 mm | 90% | 6.7 m/s | 0.4 |
| 1993 | 7.2°C | 5.6°C | 3.9°C | 11.8°C | 1.2°C | 147 mm | 91% | 6.8 m/s | 0.4 |
| 1992 | 7.1°C | 5.6°C | 4.1°C | 9.8°C | 1.7°C | 85 mm | 91% | 5.2 m/s | 0.4 |
| 1991 | 8.3°C | 6.8°C | 5.4°C | 11.8°C | 1.8°C | 59 mm | 90% | 5.3 m/s | 0.4 |
| 1990 | 7.1°C | 5.5°C | 3.8°C | 11.0°C | 1.2°C | 96 mm | 88% | 6 m/s | 0.4 |
| 1989 | 7.4°C | 6.1°C | 4.7°C | 11.5°C | 2.7°C | 75 mm | 87% | 5 m/s | 0.4 |
| 1988 | 9.3°C | 7.8°C | 6.3°C | 11.1°C | 3.5°C | 73 mm | 93% | 6.2 m/s | 0.4 |
| 1987 | 8.3°C | 7.1°C | 5.9°C | 11.8°C | 2.4°C | 73 mm | 89% | 5.6 m/s | 0.4 |
| 1986 | 7.8°C | 5.9°C | 4.0°C | 11.9°C | 1.6°C | 152 mm | 91% | 6.8 m/s | 0.4 |
| 1985 | 8.2°C | 6.8°C | 5.4°C | 12.7°C | -0.5°C | 92 mm | 91% | 5.7 m/s | 0.4 |
| 1984 | 7.9°C | 6.4°C | 4.9°C | 11.0°C | 1.0°C | 105 mm | 92% | 5.4 m/s | 0.4 |
| 1983 | 8.7°C | 7.3°C | 6.0°C | 11.7°C | 3.3°C | 131 mm | 90% | 6.3 m/s | — |
| 1982 | 7.1°C | 5.4°C | 3.8°C | 11.2°C | 1.2°C | 128 mm | 91% | 6.2 m/s | — |
| 1981 | 5.0°C | 3.9°C | 2.7°C | 10.4°C | -1.5°C | 80 mm | 87% | 5.2 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around 7.9°C with lows near 5.1°C (mean 6.5°C), based on 45 years of NASA POWER data.
December averages 107 mm of rainfall in Belfast, a relatively wet time of year. The wettest on record was 198 mm in 2015.
The hottest December reached 13.3°C in 1994. The coldest dipped to -1.5°C in 1981.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 1.3°C. Daytime highs moved from 7.4°C to 8.7°C and overnight lows from 4.6°C to 5.9°C over the same span.
December is one of the cooler months of the year in Belfast and a relatively wet time of year, so plan for around 7.9°C daytime highs and 5.1°C at night.
Not quite — December is the 4th coolest month in Belfast, averaging 6.5°C.
For December in Belfast, pack warm layers and a jacket for chilly mornings, with typical highs of 7.9°C and lows of 5.1°C. Bring an umbrella or light rain jacket too.
Relative humidity in December averages 90% — quite humid.
Average wind speed in December is 5.8 m/s. The windiest December on record averaged 7.4 m/s (2013).
The wettest December on record was 2015 with 198 mm. On average, December sees 107 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 Belfast 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.
