December is one of the cooler months of the year in Sydney Mines, with average highs near 2.3°C and lows around -2.6°C (mean -0.2°C). It is a relatively wet time of year, averaging 115 mm of rainfall and 85% relative humidity across the period.
December is one of the cooler months of the year in Sydney Mines. Across 45 years of records, the warmest December in Sydney Mines was 2010 — when the month averaged 3.3°C — while the coldest was 1989 at -5.4°C. Typical December days reach 2.3°C with nights near -2.6°C. The long-term trend is warming, about 0.5°C per decade.
December is a relatively wet time of year in Sydney Mines, averaging 115 mm of rainfall. The wettest December on record was 2010 with 312 mm, while the driest was 1989 at 24 mm.
Relative humidity in Sydney Mines during December averages 85%. The most humid December was 2010 at 88%, and the least humid was 1995 at 81%.
December receives about 0.8 kWh/m²/day of solar energy in Sydney Mines. The sunniest Decembers were 2017, 2021 and 2024, among others at 0.9 kWh/m²/day, and the cloudiest were 2007, 2008 and 2013, among others at 0.7.
Average wind speed in Sydney Mines during December is 7 m/s. The windiest December was 2025 at 8.2 m/s, while the calmest was 2001 at 5.7 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | -1.4°C | -0.2°C | -0.3°C | 0.4°C | 1.2°C | +2.6°C |
| Avg High | 1.2°C | 2.2°C | 2.1°C | 2.7°C | 3.4°C | +2.2°C |
| Avg Low | -4.0°C | -2.6°C | -2.7°C | -1.9°C | -1.1°C | +2.9°C |
| Avg Rain | 94 mm | 88 mm | 135 mm | 142 mm | 115 mm | +21 mm |
December temperatures in Sydney Mines have risen by about 1.5°C between 1981–1985 and 2021–2025.
December has ranged from a record low of -15.1°C (1993) to a record high of 12.8°C (2011).
Rainfall in December is a relatively wet time of year, averaging 115 mm, with a wettest year of 312 mm.
A quieter season to visit Sydney Mines
If your dates are flexible, the more temperate months of August and July tend to be the most comfortable for visiting Sydney Mines. That said, December — with days averaging 2.3°C and nights around -2.6°C (mean -0.2°C) and higher rainfall (115 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 | 1.7°C | -0.8°C | -3.2°C | 9.5°C | -8.3°C | 101 mm | 82% | 8.2 m/s | — |
| 2024 | 2.9°C | 0.8°C | -1.4°C | 10.7°C | -5.7°C | 80 mm | 84% | 5.8 m/s | 0.9 |
| 2023 | 3.8°C | 1.7°C | -0.5°C | 10.8°C | -6.4°C | 177 mm | 86% | 6.9 m/s | 0.8 |
| 2022 | 3.9°C | 1.9°C | -0.1°C | 10.8°C | -5.2°C | 113 mm | 84% | 6.8 m/s | 0.8 |
| 2021 | 3.3°C | 0.7°C | -2.0°C | 12.1°C | -7.7°C | 124 mm | 82% | 7.3 m/s | 0.9 |
| 2020 | 5.0°C | 2.8°C | 0.5°C | 11.8°C | -5.2°C | 96 mm | 86% | 6.9 m/s | 0.8 |
| 2019 | 2.1°C | -0.2°C | -2.5°C | 10.1°C | -6.5°C | 96 mm | 83% | 7.2 m/s | 0.8 |
| 2018 | 0.4°C | -1.7°C | -3.7°C | 8.5°C | -8.6°C | 121 mm | 85% | 6.6 m/s | 0.8 |
| 2017 | 2.0°C | -0.5°C | -3.0°C | 10.0°C | -13.2°C | 127 mm | 83% | 6.8 m/s | 0.9 |
| 2016 | 1.9°C | -0.8°C | -3.5°C | 9.2°C | -13.5°C | 140 mm | 86% | 7.2 m/s | 0.8 |
| 2015 | 3.3°C | 1.2°C | -0.8°C | 10.3°C | -6.3°C | 118 mm | 86% | 5.8 m/s | 0.8 |
| 2014 | 3.8°C | 1.4°C | -0.9°C | 11.0°C | -10.2°C | 118 mm | 86% | 6.4 m/s | 0.8 |
| 2013 | 0.3°C | -2.3°C | -4.9°C | 9.0°C | -10.3°C | 171 mm | 87% | 6.6 m/s | 0.7 |
| 2012 | 4.2°C | 1.8°C | -0.6°C | 10.8°C | -4.2°C | 111 mm | 85% | 6.9 m/s | 0.8 |
| 2011 | 4.1°C | 1.6°C | -0.8°C | 12.8°C | -5.9°C | 100 mm | 84% | 6.2 m/s | 0.8 |
| 2010 🔥 🌧️ | 4.9°C | 3.3°C | 1.7°C | 8.8°C | -2.6°C | 312 mm | 88% | 8 m/s | 0.8 |
| 2009 | 1.9°C | -0.1°C | -2.0°C | 9.5°C | -9.1°C | 141 mm | 87% | 7.2 m/s | 0.8 |
| 2008 | 3.7°C | 0.7°C | -2.4°C | 11.0°C | -8.3°C | 178 mm | 84% | 7.5 m/s | 0.7 |
| 2007 | 0.3°C | -2.0°C | -4.3°C | 6.5°C | -9.1°C | 128 mm | 84% | 7.2 m/s | 0.7 |
| 2006 | 2.6°C | 0.4°C | -1.9°C | 11.2°C | -6.5°C | 123 mm | 84% | 7.3 m/s | 0.8 |
| 2005 | 2.4°C | 0.2°C | -2.0°C | 8.4°C | -8.2°C | 135 mm | 86% | 6.5 m/s | 0.7 |
| 2004 | 2.0°C | -0.8°C | -3.6°C | 8.5°C | -12.4°C | 156 mm | 85% | 7.1 m/s | 0.7 |
| 2003 | 2.9°C | 0.6°C | -1.6°C | 8.5°C | -5.9°C | 146 mm | 87% | 6.7 m/s | 0.8 |
| 2002 | 0.9°C | -1.3°C | -3.5°C | 6.4°C | -12.0°C | 108 mm | 86% | 6.9 m/s | 0.8 |
| 2001 | 2.9°C | 0.7°C | -1.5°C | 11.3°C | -6.5°C | 100 mm | 86% | 5.7 m/s | 0.8 |
| 2000 | 1.2°C | -1.4°C | -4.0°C | 10.0°C | -10.7°C | 137 mm | 84% | 8.1 m/s | 0.8 |
| 1999 | 3.2°C | 0.9°C | -1.4°C | 10.1°C | -10.6°C | 157 mm | 85% | 7 m/s | 0.7 |
| 1998 | 1.7°C | -0.7°C | -3.2°C | 8.9°C | -11.6°C | 89 mm | 83% | 7.3 m/s | 0.8 |
| 1997 | 1.4°C | -0.7°C | -2.7°C | 5.5°C | -7.8°C | 92 mm | 85% | 6.4 m/s | 0.8 |
| 1996 | 3.9°C | 1.5°C | -1.0°C | 10.9°C | -12.9°C | 118 mm | 85% | 7.2 m/s | 0.8 |
| 1995 | 1.4°C | -0.6°C | -2.5°C | 7.7°C | -8.9°C | 39 mm | 81% | 7.1 m/s | 0.9 |
| 1994 | 1.8°C | -0.4°C | -2.6°C | 7.8°C | -6.6°C | 50 mm | 83% | 6.9 m/s | 0.8 |
| 1993 | 2.5°C | -0.1°C | -2.6°C | 10.1°C | -15.1°C | 147 mm | 87% | 7.1 m/s | 0.7 |
| 1992 | 1.3°C | -1.0°C | -3.4°C | 7.6°C | -10.1°C | 50 mm | 83% | 6.9 m/s | 0.8 |
| 1991 | 1.3°C | -1.5°C | -4.4°C | 10.2°C | -9.8°C | 48 mm | 83% | 6.8 m/s | 0.9 |
| 1990 | 3.8°C | 0.7°C | -2.4°C | 9.5°C | -10.1°C | 96 mm | 84% | 7.5 m/s | 0.8 |
| 1989 ❄️ | -2.8°C | -5.4°C | -8.1°C | 6.2°C | -14.5°C | 24 mm | 84% | 8 m/s | 0.9 |
| 1988 | 0.6°C | -2.0°C | -4.7°C | 7.5°C | -9.9°C | 40 mm | 82% | 6.7 m/s | 0.8 |
| 1987 | 1.0°C | -0.8°C | -2.6°C | 9.1°C | -9.2°C | 92 mm | 84% | 7.5 m/s | 0.8 |
| 1986 | 1.4°C | -1.4°C | -4.2°C | 7.9°C | -11.8°C | 30 mm | 82% | 7.1 m/s | 0.8 |
| 1985 | 0.6°C | -2.5°C | -5.7°C | 9.3°C | -11.5°C | 56 mm | 82% | 6.9 m/s | 0.8 |
| 1984 | 2.6°C | -0.6°C | -3.7°C | 9.5°C | -13.9°C | 124 mm | 85% | 7.2 m/s | 0.7 |
| 1983 | 1.4°C | -1.3°C | -4.0°C | 8.7°C | -13.7°C | 184 mm | 85% | 7.3 m/s | — |
| 1982 | 2.9°C | -0.1°C | -3.0°C | 11.1°C | -11.1°C | 133 mm | 85% | 7 m/s | — |
| 1981 | 3.4°C | 1.7°C | -0.1°C | 10.0°C | -6.1°C | 165 mm | 85% | 6.8 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 -2.6°C (mean -0.2°C), based on 45 years of NASA POWER data.
December averages 115 mm of rainfall in Sydney Mines, a relatively wet time of year. The wettest on record was 312 mm in 2010.
The hottest December reached 12.8°C in 2011. The coldest dipped to -15.1°C in 1993.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 1.5°C. Daytime highs moved from 2.2°C to 3.1°C and overnight lows from -3.3°C to -1.4°C over the same span.
December is one of the cooler months of the year in Sydney Mines and a relatively wet time of year, so plan for around 2.3°C daytime highs and -2.6°C at night.
Not quite — December is the 4th coolest month in Sydney Mines, averaging -0.2°C.
For December in Sydney Mines, pack warm layers and a jacket for chilly mornings, with typical highs of 2.3°C and lows of -2.6°C. Bring an umbrella or light rain jacket too.
Relative humidity in December averages 85% — quite humid.
Average wind speed in December is 7 m/s. The windiest December on record averaged 8.2 m/s (2025).
The wettest December on record was 2010 with 312 mm. On average, December sees 115 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 Sydney Mines 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.
