December is one of the warmer months of the year in Merredin, with average highs near 33°C and lows around 15.7°C (mean 24.4°C). It is one of the drier months, averaging 13 mm of rainfall and 38% relative humidity across the period.
December is one of the warmer months of the year in Merredin. Across 45 years of records, the warmest December in Merredin was 2019 — when the month averaged 28.4°C — while the coldest were 1985 and 2005 at 21.7°C. Typical December days reach 33°C with nights near 15.7°C. The long-term trend is warming, about 0.4°C per decade.
December is one of the drier months in Merredin, averaging 13 mm of rainfall. The wettest December on record was 2011 with 63 mm, while the driest was 1997 at 0 mm.
Relative humidity in Merredin during December averages 38%. The most humid December was 2011 at 50%, and the least humid was 2019 at 30%.
December receives about 8.6 kWh/m²/day of solar energy in Merredin. The sunniest Decembers were 1985 and 1990 at 9.1 kWh/m²/day, and the cloudiest was 2010 at 7.5.
Average wind speed in Merredin during December is 4.2 m/s. The windiest December was 1993 at 4.7 m/s, while the calmest was 2012 at 3.5 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 23.5°C | 24.3°C | 24.2°C | 24.7°C | 25.3°C | +1.8°C |
| Avg High | 32.1°C | 32.9°C | 33.0°C | 33.2°C | 34.1°C | +2°C |
| Avg Low | 14.9°C | 15.7°C | 15.3°C | 16.2°C | 16.5°C | +1.6°C |
| Avg Rain | 14 mm | 14 mm | 11 mm | 20 mm | 4 mm | -10 mm |
December temperatures in Merredin have risen by about 2.3°C between 1981–1985 and 2021–2025.
December has ranged from a record low of 6.8°C (2020) to a record high of 44.2°C (2009).
Rainfall in December is one of the drier months, averaging 13 mm, with a wettest year of 63 mm.
One of the best times to visit Merredin
December is one of the best times to visit Merredin. Expect days averaging 33°C and nights around 15.7°C (mean 24.4°C) — warmer than Merredin's yearly average — with low rainfall (13 mm), so conditions are generally comfortable for sightseeing and outdoor plans.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 34.5°C | 25.5°C | 16.5°C | 41.3°C | 10.6°C | 11 mm | 35% | 4.4 m/s | — |
| 2024 | 35.5°C | 26.6°C | 17.8°C | 42.4°C | 10.7°C | 4 mm | 36% | 4.1 m/s | 8.7 |
| 2023 | 34.4°C | 25.8°C | 17.2°C | 39.1°C | 11.2°C | 2 mm | 36% | 4.6 m/s | 8.5 |
| 2022 | 32.7°C | 24.2°C | 15.7°C | 40.2°C | 10.7°C | 2 mm | 39% | 4.3 m/s | 8.7 |
| 2021 | 34.0°C | 25.2°C | 16.4°C | 40.2°C | 10.9°C | 3 mm | 37% | 4.2 m/s | 8.9 |
| 2020 | 33.5°C | 24.5°C | 15.6°C | 42.0°C | 6.8°C | 2 mm | 34% | 4.2 m/s | 8.8 |
| 2019 🔥 | 37.8°C | 28.4°C | 19.0°C | 43.3°C | 10.6°C | 2 mm | 30% | 3.8 m/s | 8.8 |
| 2018 | 33.7°C | 25.0°C | 16.3°C | 40.0°C | 10.9°C | 21 mm | 37% | 3.7 m/s | 8.5 |
| 2017 | 32.8°C | 24.4°C | 16.0°C | 39.5°C | 10.5°C | 7 mm | 36% | 4.1 m/s | 8.4 |
| 2016 | 32.2°C | 23.6°C | 15.0°C | 41.2°C | 9.8°C | 27 mm | 39% | 4.2 m/s | 8.7 |
| 2015 | 32.7°C | 24.3°C | 15.8°C | 42.4°C | 10.3°C | 9 mm | 37% | 4.1 m/s | 8.4 |
| 2014 | 32.6°C | 23.7°C | 14.9°C | 42.8°C | 10.5°C | 6 mm | 38% | 4.2 m/s | 9 |
| 2013 | 34.5°C | 25.5°C | 16.5°C | 42.8°C | 10.0°C | 6 mm | 34% | 3.9 m/s | 8.6 |
| 2012 | 33.2°C | 24.9°C | 16.6°C | 41.8°C | 7.7°C | 40 mm | 44% | 3.5 m/s | 8.4 |
| 2011 🌧️ | 30.9°C | 23.4°C | 15.9°C | 38.1°C | 12.1°C | 63 mm | 50% | 3.8 m/s | 7.7 |
| 2010 | 31.8°C | 23.8°C | 15.8°C | 41.5°C | 9.6°C | 16 mm | 40% | 4.2 m/s | 7.5 |
| 2009 | 34.3°C | 25.1°C | 15.9°C | 44.2°C | 10.0°C | 9 mm | 34% | 4.1 m/s | 8.8 |
| 2008 | 32.3°C | 23.6°C | 14.9°C | 40.0°C | 10.7°C | 7 mm | 43% | 4 m/s | 8.7 |
| 2007 | 30.6°C | 22.6°C | 14.6°C | 42.6°C | 7.8°C | 32 mm | 43% | 4.4 m/s | 8.1 |
| 2006 | 33.7°C | 25.0°C | 16.4°C | 41.6°C | 10.6°C | 14 mm | 37% | 3.8 m/s | 8.4 |
| 2005 | 30.7°C | 21.7°C | 12.7°C | 42.7°C | 8.3°C | 1 mm | 41% | 4.3 m/s | 9 |
| 2004 | 34.8°C | 25.7°C | 16.6°C | 43.7°C | 10.2°C | 6 mm | 35% | 4.5 m/s | 8.8 |
| 2003 | 34.2°C | 24.8°C | 15.5°C | 43.2°C | 8.4°C | 9 mm | 37% | 4.1 m/s | 8.9 |
| 2002 | 33.5°C | 24.9°C | 16.3°C | 42.6°C | 8.2°C | 25 mm | 38% | 4.5 m/s | 8.3 |
| 2001 | 30.3°C | 22.0°C | 13.6°C | 37.2°C | 8.5°C | 2 mm | 42% | 4.3 m/s | 8.4 |
| 2000 | 35.9°C | 26.4°C | 16.8°C | 42.4°C | 9.5°C | 2 mm | 33% | 4.2 m/s | 8.7 |
| 1999 | 33.0°C | 24.9°C | 16.8°C | 40.4°C | 10.9°C | 35 mm | 38% | 4.4 m/s | 8.2 |
| 1998 | 33.2°C | 25.0°C | 16.8°C | 41.4°C | 7.9°C | 7 mm | 40% | 4.3 m/s | 8.2 |
| 1997 | 35.2°C | 26.0°C | 16.8°C | 44.0°C | 10.9°C | 0 mm | 34% | 4.5 m/s | 8.8 |
| 1996 | 31.6°C | 22.8°C | 13.9°C | 40.0°C | 9.7°C | 1 mm | 40% | 4.5 m/s | 8.8 |
| 1995 | 30.7°C | 22.5°C | 14.2°C | 39.8°C | 10.1°C | 41 mm | 46% | 4.5 m/s | 7.8 |
| 1994 | 34.5°C | 25.5°C | 16.5°C | 43.3°C | 10.3°C | 9 mm | 33% | 4.2 m/s | 8.7 |
| 1993 | 32.7°C | 23.9°C | 15.2°C | 41.6°C | 9.0°C | 3 mm | 35% | 4.7 m/s | 8.9 |
| 1992 | 31.9°C | 23.0°C | 14.1°C | 41.0°C | 8.4°C | 5 mm | 37% | 4.3 m/s | 8.7 |
| 1991 | 33.1°C | 24.9°C | 16.7°C | 40.6°C | 12.3°C | 37 mm | 39% | 4.1 m/s | 8.3 |
| 1990 | 33.1°C | 24.3°C | 15.5°C | 40.5°C | 9.7°C | 1 mm | 35% | 4.1 m/s | 9.1 |
| 1989 | 32.9°C | 23.9°C | 14.8°C | 40.1°C | 10.5°C | 3 mm | 35% | 4.2 m/s | 8.7 |
| 1988 | 31.6°C | 23.4°C | 15.2°C | 41.5°C | 9.4°C | 22 mm | 42% | 4.2 m/s | 8.4 |
| 1987 | 33.6°C | 25.1°C | 16.6°C | 41.6°C | 9.2°C | 37 mm | 39% | 4.1 m/s | 8.6 |
| 1986 | 32.6°C | 23.5°C | 14.4°C | 42.4°C | 8.6°C | 5 mm | 36% | 4.1 m/s | 8.8 |
| 1985 ❄️ | 30.5°C | 21.7°C | 12.8°C | 40.5°C | 8.9°C | 2 mm | 37% | 4.3 m/s | 9.1 |
| 1984 | 31.6°C | 22.9°C | 14.1°C | 40.3°C | 8.5°C | 3 mm | 36% | 4 m/s | 8.8 |
| 1983 | 31.2°C | 23.4°C | 15.5°C | 39.5°C | 8.7°C | 30 mm | 49% | 4.1 m/s | — |
| 1982 | 34.4°C | 25.7°C | 17.1°C | 40.9°C | 10.8°C | 7 mm | 37% | 3.9 m/s | — |
| 1981 | 30.6°C | 22.1°C | 13.7°C | 38.0°C | 10.2°C | 17 mm | 39% | 4.3 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around 33°C with lows near 15.7°C (mean 24.4°C), based on 45 years of NASA POWER data.
December averages 13 mm of rainfall in Merredin, one of the drier months. The wettest on record was 63 mm in 2011.
The hottest December reached 44.2°C in 2009. The coldest dipped to 6.8°C in 2020.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 2.3°C. Daytime highs moved from 31.7°C to 34.2°C and overnight lows from 14.6°C to 16.7°C over the same span.
December is one of the warmer months of the year in Merredin and one of the drier months, so plan for around 33°C daytime highs and 15.7°C at night.
Not quite — December is the 10th coolest month in Merredin, averaging 24.4°C.
For December in Merredin, pack light, breathable clothing and sun protection, with typical highs of 33°C and lows of 15.7°C.
Relative humidity in December averages 38% — relatively dry.
Average wind speed in December is 4.2 m/s. The windiest December on record averaged 4.7 m/s (1993).
The wettest December on record was 2011 with 63 mm. On average, December sees 13 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 Merredin 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.
