December is one of the cooler months of the year in Brentwood, with average highs near 9.3°C and lows around -0.6°C (mean 4.4°C). It is a relatively wet time of year, averaging 127 mm of rainfall and 84% relative humidity across the period.
December is one of the cooler months of the year in Brentwood. Across 45 years of records, the warmest December in Brentwood was 2015 — when the month averaged 10.4°C — while the coldest was 1989 at -2.4°C. Typical December days reach 9.3°C with nights near -0.6°C. The long-term trend is warming, about 0.7°C per decade.
December is a relatively wet time of year in Brentwood, averaging 127 mm of rainfall. The wettest December on record was 1990 with 343 mm, while the driest was 1985 at 38 mm.
Relative humidity in Brentwood during December averages 84%. The most humid December was 1984 at 90%, and the least humid was 2023 at 75%.
December receives about 2 kWh/m²/day of solar energy in Brentwood. The sunniest Decembers were 1988, 2001 and 2004, among others at 2.4 kWh/m²/day, and the cloudiest were 1992 and 2014 at 1.6.
Average wind speed in Brentwood during December is 1.9 m/s. The windiest Decembers were 1982 and 2008 at 2.4 m/s, while the calmest was 1986 at 1.5 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 2.8°C | 4.6°C | 3.7°C | 5.3°C | 6.1°C | +3.3°C |
| Avg High | 7.6°C | 9.6°C | 8.8°C | 10.0°C | 11.5°C | +3.9°C |
| Avg Low | -2.0°C | -0.4°C | -1.3°C | 0.5°C | 0.7°C | +2.7°C |
| Avg Rain | 124 mm | 145 mm | 115 mm | 136 mm | 111 mm | -12 mm |
December temperatures in Brentwood have risen by about 3.3°C between 1981–1985 and 2021–2025.
December has ranged from a record low of -22.1°C (1989) to a record high of 24.2°C (1998).
Rainfall in December is a relatively wet time of year, averaging 127 mm, with a wettest year of 343 mm.
Daytime highs and overnight lows have shifted differently — highs rose about 0.8°C per decade while lows rose 0.6°C per decade, widening the gap between day and night.
A quieter season to visit Brentwood
If your dates are flexible, the more temperate months of September and June tend to be the most comfortable for visiting Brentwood. That said, December — with days averaging 9.3°C and nights around -0.6°C (mean 4.4°C) and higher rainfall (127 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 | 10.2°C | 4.9°C | -0.4°C | 22.4°C | -10.1°C | 61 mm | 80% | 1.9 m/s | — |
| 2024 | 11.1°C | 6.0°C | 1.0°C | 17.3°C | -7.0°C | 136 mm | 79% | 2 m/s | 2.1 |
| 2023 | 13.0°C | 7.0°C | 1.0°C | 21.6°C | -6.3°C | 70 mm | 75% | 1.7 m/s | 2.3 |
| 2022 | 9.5°C | 4.5°C | -0.6°C | 21.5°C | -15.6°C | 149 mm | 84% | 1.9 m/s | 2 |
| 2021 | 16.0°C | 10.3°C | 4.6°C | 21.4°C | -4.5°C | 130 mm | 85% | 2.1 m/s | 2 |
| 2020 | 9.3°C | 3.9°C | -1.5°C | 18.6°C | -8.3°C | 122 mm | 84% | 1.8 m/s | 2.2 |
| 2019 | 12.0°C | 7.2°C | 2.4°C | 19.7°C | -5.0°C | 140 mm | 87% | 1.8 m/s | 2.1 |
| 2018 | 9.9°C | 5.4°C | 0.9°C | 19.9°C | -7.0°C | 169 mm | 88% | 1.8 m/s | 1.8 |
| 2017 | 8.3°C | 3.4°C | -1.6°C | 17.8°C | -11.8°C | 124 mm | 79% | 1.8 m/s | 2.1 |
| 2016 | 9.4°C | 4.2°C | -1.1°C | 22.1°C | -17.8°C | 171 mm | 80% | 2 m/s | 2 |
| 2015 🔥 | 15.2°C | 10.4°C | 5.6°C | 23.2°C | -3.8°C | 142 mm | 87% | 2 m/s | 1.9 |
| 2014 | 9.3°C | 5.2°C | 1.2°C | 18.5°C | -4.7°C | 110 mm | 87% | 1.6 m/s | 1.6 |
| 2013 | 8.4°C | 3.7°C | -1.0°C | 21.0°C | -9.2°C | 156 mm | 85% | 1.8 m/s | 1.9 |
| 2012 | 12.3°C | 7.2°C | 2.1°C | 21.8°C | -6.8°C | 158 mm | 84% | 2.1 m/s | 1.9 |
| 2011 | 10.5°C | 5.5°C | 0.4°C | 18.3°C | -5.4°C | 141 mm | 86% | 1.7 m/s | 2 |
| 2010 | 4.5°C | 0.3°C | -3.8°C | 17.6°C | -13.8°C | 45 mm | 80% | 2 m/s | 2 |
| 2009 | 7.5°C | 2.8°C | -1.8°C | 17.6°C | -6.3°C | 117 mm | 86% | 2 m/s | 1.9 |
| 2008 | 9.0°C | 3.5°C | -2.0°C | 20.5°C | -10.6°C | 184 mm | 81% | 2.4 m/s | 2 |
| 2007 | 11.8°C | 6.9°C | 2.1°C | 22.7°C | -5.5°C | 111 mm | 84% | 1.9 m/s | 2 |
| 2006 | 11.9°C | 6.2°C | 0.4°C | 19.6°C | -8.3°C | 81 mm | 83% | 1.8 m/s | 2.3 |
| 2005 | 7.5°C | 2.3°C | -3.0°C | 16.0°C | -7.6°C | 71 mm | 81% | 1.8 m/s | 2.1 |
| 2004 | 7.9°C | 3.2°C | -1.6°C | 18.5°C | -12.8°C | 150 mm | 86% | 2 m/s | 2.4 |
| 2003 | 8.6°C | 3.3°C | -2.0°C | 14.5°C | -6.1°C | 83 mm | 81% | 2 m/s | 2.1 |
| 2002 | 7.8°C | 3.3°C | -1.1°C | 16.5°C | -12.1°C | 150 mm | 89% | 2 m/s | 2 |
| 2001 | 11.6°C | 6.6°C | 1.6°C | 20.8°C | -8.7°C | 109 mm | 84% | 1.9 m/s | 2.4 |
| 2000 | 4.2°C | -0.9°C | -6.0°C | 17.3°C | -12.7°C | 97 mm | 81% | 1.9 m/s | 2 |
| 1999 | 11.2°C | 5.4°C | -0.3°C | 20.5°C | -6.7°C | 78 mm | 76% | 1.9 m/s | 2.3 |
| 1998 | 10.6°C | 5.6°C | 0.6°C | 24.2°C | -9.7°C | 173 mm | 83% | 1.9 m/s | 1.9 |
| 1997 | 7.9°C | 3.3°C | -1.3°C | 15.8°C | -6.9°C | 71 mm | 86% | 1.6 m/s | 1.9 |
| 1996 | 10.3°C | 5.3°C | 0.3°C | 19.3°C | -10.7°C | 136 mm | 87% | 2.1 m/s | 2 |
| 1995 | 7.3°C | 2.5°C | -2.2°C | 18.7°C | -12.3°C | 73 mm | 83% | 2 m/s | 2 |
| 1994 | 11.5°C | 6.3°C | 1.2°C | 18.9°C | -5.0°C | 78 mm | 86% | 1.6 m/s | 1.8 |
| 1993 | 8.0°C | 3.6°C | -0.8°C | 15.9°C | -10.8°C | 183 mm | 85% | 1.9 m/s | 2 |
| 1992 | 8.2°C | 3.5°C | -1.2°C | 15.9°C | -7.7°C | 96 mm | 87% | 1.9 m/s | 1.6 |
| 1991 | 10.0°C | 5.1°C | 0.3°C | 20.6°C | -6.8°C | 220 mm | 87% | 1.8 m/s | 2.1 |
| 1990 🌧️ | 10.7°C | 5.2°C | -0.3°C | 17.4°C | -11.6°C | 343 mm | 86% | 2.1 m/s | 1.8 |
| 1989 ❄️ | 2.4°C | -2.4°C | -7.2°C | 16.0°C | -22.1°C | 66 mm | 83% | 2.1 m/s | 2.3 |
| 1988 | 8.9°C | 3.6°C | -1.7°C | 17.8°C | -6.7°C | 147 mm | 82% | 2.1 m/s | 2.4 |
| 1987 | 10.4°C | 5.1°C | -0.1°C | 17.5°C | -5.5°C | 176 mm | 82% | 2.1 m/s | 1.9 |
| 1986 | 7.4°C | 3.0°C | -1.4°C | 17.0°C | -5.2°C | 113 mm | 88% | 1.5 m/s | 1.9 |
| 1985 | 5.3°C | 0.2°C | -4.9°C | 18.2°C | -14.2°C | 38 mm | 81% | 2 m/s | 2.4 |
| 1984 | 12.4°C | 8.1°C | 3.7°C | 20.5°C | -10.7°C | 90 mm | 90% | 2 m/s | 1.9 |
| 1983 | 3.5°C | -0.9°C | -5.4°C | 18.8°C | -20.6°C | 201 mm | 87% | 2.1 m/s | — |
| 1982 | 11.5°C | 7.1°C | 2.7°C | 21.5°C | -7.1°C | 201 mm | 87% | 2.4 m/s | — |
| 1981 | 6.3°C | 1.4°C | -3.5°C | 15.2°C | -12.3°C | 81 mm | 81% | 2 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around 9.3°C with lows near -0.6°C (mean 4.4°C), based on 45 years of NASA POWER data.
December averages 127 mm of rainfall in Brentwood, a relatively wet time of year. The wettest on record was 343 mm in 1990.
The hottest December reached 24.2°C in 1998. The coldest dipped to -22.1°C in 1989.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 3.3°C. Daytime highs moved from 7.8°C to 12°C and overnight lows from -1.5°C to 1.1°C over the same span.
December is one of the cooler months of the year in Brentwood and a relatively wet time of year, so plan for around 9.3°C daytime highs and -0.6°C at night.
Not quite — December is the 2nd coolest month in Brentwood, averaging 4.4°C.
For December in Brentwood, pack warm layers and a jacket for chilly mornings, with typical highs of 9.3°C and lows of -0.6°C. Bring an umbrella or light rain jacket too.
Relative humidity in December averages 84% — quite humid.
Average wind speed in December is 1.9 m/s. The windiest December on record averaged 2.4 m/s (1982).
The wettest December on record was 1990 with 343 mm. On average, December sees 127 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 Brentwood 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.
