December is one of the warmer months of the year in Whyalla, with average highs near 28.7°C and lows around 17.2°C (mean 23°C). It is about average for rainfall, averaging 21 mm of rainfall and 50% relative humidity across the period.
December is one of the warmer months of the year in Whyalla. Across 45 years of records, the warmest December in Whyalla was 2019 — when the month averaged 26.2°C — while the coldest was 2001 at 20°C. Typical December days reach 28.7°C with nights near 17.2°C. The long-term trend is warming, about 0.4°C per decade.
December is about average for rainfall in Whyalla, averaging 21 mm of rainfall. The wettest December on record was 1992 with 96 mm, while the driest were 2016, 2017 and 2018 at 0 mm.
Relative humidity in Whyalla during December averages 50%. The most humid December was 1992 at 65%, and the least humid was 2015 at 41%.
December receives about 7.8 kWh/m²/day of solar energy in Whyalla. The sunniest December was 2021 at 8.5 kWh/m²/day, and the cloudiest was 1992 at 6.7.
Average wind speed in Whyalla during December is 4.5 m/s. The windiest Decembers were 2020 and 2023 at 5 m/s, while the calmest was 2015 at 3.9 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 22.5°C | 22.2°C | 22.9°C | 24.0°C | 23.2°C | +0.7°C |
| Avg High | 28.4°C | 27.8°C | 28.7°C | 29.9°C | 28.9°C | +0.5°C |
| Avg Low | 16.7°C | 16.6°C | 17.1°C | 18.2°C | 17.5°C | +0.8°C |
| Avg Rain | 13 mm | 32 mm | 25 mm | 16 mm | 13 mm | -1 mm |
December temperatures in Whyalla have risen by about 0.7°C between 1981–1985 and 2021–2025.
December has ranged from a record low of 11.1°C (1995) to a record high of 44.7°C (2019).
Rainfall in December is about average for rainfall, averaging 21 mm, with a wettest year of 96 mm.
One of the best times to visit Whyalla
December is one of the best times to visit Whyalla. Expect days averaging 28.7°C and nights around 17.2°C (mean 23°C) — warmer than Whyalla's yearly average — with low rainfall (21 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 | 30.0°C | 23.9°C | 17.7°C | 39.5°C | 13.0°C | 13 mm | 45% | 4.6 m/s | — |
| 2024 | 29.9°C | 24.1°C | 18.4°C | 39.3°C | 14.7°C | 12 mm | 51% | 4.3 m/s | 8.1 |
| 2023 | 28.8°C | 23.1°C | 17.5°C | 40.1°C | 14.2°C | 15 mm | 52% | 5 m/s | 7.1 |
| 2022 | 28.3°C | 22.7°C | 17.1°C | 38.6°C | 12.8°C | 20 mm | 52% | 4.5 m/s | 8.2 |
| 2021 | 28.7°C | 23.0°C | 17.3°C | 38.3°C | 11.9°C | 6 mm | 50% | 4.5 m/s | 8.5 |
| 2020 | 27.7°C | 22.3°C | 16.9°C | 36.6°C | 13.5°C | 11 mm | 50% | 5 m/s | 7.9 |
| 2019 🔥 | 32.6°C | 26.2°C | 19.7°C | 44.7°C | 12.4°C | 1 mm | 44% | 4.5 m/s | 8.2 |
| 2018 | 30.9°C | 25.0°C | 19.1°C | 40.7°C | 14.0°C | 0 mm | 47% | 4.7 m/s | 7.4 |
| 2017 | 29.3°C | 23.6°C | 18.0°C | 40.1°C | 14.3°C | 0 mm | 49% | 4.5 m/s | 7.4 |
| 2016 | 29.9°C | 24.1°C | 18.4°C | 40.1°C | 13.0°C | 0 mm | 50% | 4.5 m/s | 7.5 |
| 2015 | 32.1°C | 25.9°C | 19.7°C | 41.4°C | 13.0°C | 20 mm | 41% | 3.9 m/s | 8.1 |
| 2014 | 28.8°C | 23.2°C | 17.6°C | 35.7°C | 14.8°C | 14 mm | 52% | 4.5 m/s | 8.2 |
| 2013 | 29.8°C | 23.7°C | 17.7°C | 41.1°C | 12.2°C | 21 mm | 48% | 4.2 m/s | 7.7 |
| 2012 | 29.2°C | 23.5°C | 17.7°C | 38.1°C | 13.3°C | 8 mm | 48% | 4.5 m/s | 8.3 |
| 2011 | 28.5°C | 23.0°C | 17.4°C | 39.0°C | 13.2°C | 44 mm | 51% | 4.2 m/s | 7.8 |
| 2010 | 27.6°C | 22.1°C | 16.6°C | 39.3°C | 12.9°C | 49 mm | 56% | 4.3 m/s | 7.7 |
| 2009 | 29.0°C | 23.2°C | 17.3°C | 38.9°C | 13.6°C | 12 mm | 50% | 4.2 m/s | 8.3 |
| 2008 | 27.1°C | 21.9°C | 16.7°C | 33.3°C | 13.4°C | 65 mm | 57% | 4.1 m/s | 7.5 |
| 2007 | 29.7°C | 23.7°C | 17.7°C | 39.3°C | 13.9°C | 34 mm | 48% | 4.3 m/s | 7.9 |
| 2006 | 28.9°C | 23.0°C | 17.1°C | 39.7°C | 12.6°C | 28 mm | 46% | 4.6 m/s | 8.1 |
| 2005 | 29.8°C | 23.2°C | 16.7°C | 41.1°C | 11.8°C | 22 mm | 50% | 4.5 m/s | 7.9 |
| 2004 | 27.8°C | 22.2°C | 16.6°C | 37.2°C | 13.1°C | 29 mm | 53% | 4.5 m/s | 8 |
| 2003 | 30.1°C | 24.0°C | 17.9°C | 39.3°C | 13.3°C | 20 mm | 50% | 4.1 m/s | 7.9 |
| 2002 | 29.8°C | 23.5°C | 17.3°C | 41.1°C | 12.8°C | 8 mm | 45% | 4.8 m/s | 7.7 |
| 2001 ❄️ | 25.1°C | 20.0°C | 14.9°C | 34.4°C | 12.5°C | 17 mm | 59% | 4.6 m/s | 7.4 |
| 2000 | 30.0°C | 24.2°C | 18.5°C | 40.1°C | 14.1°C | 9 mm | 48% | 4.3 m/s | 8.1 |
| 1999 | 27.1°C | 21.9°C | 16.7°C | 36.8°C | 13.4°C | 30 mm | 53% | 4.9 m/s | 7.7 |
| 1998 | 28.7°C | 23.0°C | 17.3°C | 37.4°C | 13.5°C | 16 mm | 52% | 4.5 m/s | 8 |
| 1997 | 29.2°C | 23.4°C | 17.5°C | 35.5°C | 14.2°C | 50 mm | 55% | 4 m/s | 8 |
| 1996 | 27.6°C | 22.0°C | 16.3°C | 36.7°C | 13.3°C | 10 mm | 51% | 4.7 m/s | 7.9 |
| 1995 | 27.0°C | 21.5°C | 15.9°C | 36.5°C | 11.1°C | 23 mm | 50% | 4.4 m/s | 7.6 |
| 1994 | 30.7°C | 24.2°C | 17.7°C | 41.0°C | 12.7°C | 5 mm | 43% | 4.4 m/s | 8.1 |
| 1993 | 26.4°C | 21.5°C | 16.5°C | 33.8°C | 12.8°C | 57 mm | 55% | 4.6 m/s | 7.3 |
| 1992 🌧️ | 25.6°C | 20.9°C | 16.2°C | 33.6°C | 13.7°C | 96 mm | 65% | 4.4 m/s | 6.7 |
| 1991 | 27.2°C | 21.5°C | 15.9°C | 38.5°C | 12.4°C | 2 mm | 53% | 4.7 m/s | 8.2 |
| 1990 | 28.1°C | 22.2°C | 16.3°C | 37.3°C | 12.2°C | 36 mm | 52% | 4.4 m/s | 7.7 |
| 1989 | 29.3°C | 23.2°C | 17.0°C | 39.8°C | 12.8°C | 16 mm | 49% | 4.3 m/s | 8 |
| 1988 | 28.4°C | 22.9°C | 17.4°C | 36.7°C | 13.5°C | 17 mm | 54% | 4.7 m/s | 7.7 |
| 1987 | 28.5°C | 22.5°C | 16.6°C | 39.3°C | 11.6°C | 12 mm | 48% | 4.7 m/s | 8.1 |
| 1986 | 26.1°C | 20.8°C | 15.4°C | 37.4°C | 11.8°C | 15 mm | 54% | 4.7 m/s | 7.7 |
| 1985 | 26.3°C | 20.6°C | 14.8°C | 35.3°C | 12.4°C | 19 mm | 53% | 4.8 m/s | 7.8 |
| 1984 | 29.1°C | 23.0°C | 16.9°C | 37.6°C | 12.5°C | 6 mm | 47% | 4.4 m/s | 7.6 |
| 1983 | 29.8°C | 23.9°C | 18.0°C | 38.9°C | 13.2°C | 21 mm | 48% | 4 m/s | — |
| 1982 | 29.1°C | 23.2°C | 17.3°C | 37.9°C | 12.7°C | 10 mm | 47% | 4.4 m/s | — |
| 1981 | 28.7°C | 22.6°C | 16.5°C | 38.4°C | 12.7°C | 4 mm | 48% | 4.8 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around 28.7°C with lows near 17.2°C (mean 23°C), based on 45 years of NASA POWER data.
December averages 21 mm of rainfall in Whyalla, about average for rainfall. The wettest on record was 96 mm in 1992.
The hottest December reached 44.7°C in 2019. The coldest dipped to 11.1°C in 1995.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 0.7°C. Daytime highs moved from 28.6°C to 29.1°C and overnight lows from 16.7°C to 17.6°C over the same span.
December is one of the warmer months of the year in Whyalla and about average for rainfall, so plan for around 28.7°C daytime highs and 17.2°C at night.
Not quite — December is the 10th coolest month in Whyalla, averaging 23°C.
For December in Whyalla, pack light layers you can adjust through the day, with typical highs of 28.7°C and lows of 17.2°C.
Relative humidity in December averages 50% — relatively dry.
Average wind speed in December is 4.5 m/s. The windiest December on record averaged 5 m/s (2020).
The wettest December on record was 1992 with 96 mm. On average, December sees 21 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 Whyalla 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.
