September is one of the cooler months of the year in Whyalla, with average highs near 20.6°C and lows around 10.1°C (mean 15.4°C). It is about average for rainfall, averaging 28 mm of rainfall and 62% relative humidity across the period.
September is one of the cooler months of the year in Whyalla. Across 45 years of records, the warmest September in Whyalla was 2023 — when the month averaged 18.1°C — while the coldest was 1984 at 12.6°C. Typical September days reach 20.6°C with nights near 10.1°C. The long-term trend is warming, about 0.4°C per decade.
September is about average for rainfall in Whyalla, averaging 28 mm of rainfall. The wettest September on record was 2016 with 83 mm, while the driest was 2018 at 3 mm.
Relative humidity in Whyalla during September averages 62%. The most humid September was 2010 at 76%, and the least humid was 2023 at 53%.
September receives about 5.1 kWh/m²/day of solar energy in Whyalla. The sunniest September was 2023 at 5.7 kWh/m²/day, and the cloudiest was 2010 at 4.3.
Average wind speed in Whyalla during September is 4 m/s. The windiest September was 1996 at 4.7 m/s, while the calmest was 1997 at 3.3 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 14.7°C | 15.0°C | 15.7°C | 15.5°C | 16.2°C | +1.5°C |
| Avg High | 19.8°C | 20.0°C | 21.0°C | 20.7°C | 21.6°C | +1.8°C |
| Avg Low | 9.5°C | 10.0°C | 10.3°C | 10.2°C | 10.9°C | +1.4°C |
| Avg Rain | 23 mm | 39 mm | 30 mm | 27 mm | 17 mm | -6 mm |
September temperatures in Whyalla have risen by about 1.6°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 5.3°C (1995) to a record high of 32.1°C (1998).
Rainfall in September is about average for rainfall, averaging 28 mm, with a wettest year of 83 mm.
A quieter season to visit Whyalla
If your dates are flexible, the more temperate months of March and December tend to be the most comfortable for visiting Whyalla. That said, September — with days averaging 20.6°C and nights around 10.1°C (mean 15.4°C) and low rainfall (28 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 | 21.7°C | 16.3°C | 11.0°C | 29.1°C | 8.0°C | 11 mm | 60% | 3.9 m/s | 5.2 |
| 2024 | 21.4°C | 15.8°C | 10.1°C | 29.6°C | 6.5°C | 7 mm | 58% | 3.9 m/s | 5.2 |
| 2023 🔥 | 24.1°C | 18.1°C | 12.1°C | 32.0°C | 7.6°C | 3 mm | 53% | 3.6 m/s | 5.7 |
| 2022 | 19.2°C | 14.6°C | 10.1°C | 25.2°C | 6.6°C | 41 mm | 69% | 4.1 m/s | 4.8 |
| 2021 | 21.2°C | 15.8°C | 10.5°C | 29.5°C | 8.1°C | 9 mm | 58% | 4.1 m/s | 5.3 |
| 2020 | 22.0°C | 16.7°C | 11.5°C | 28.2°C | 6.9°C | 32 mm | 59% | 4.2 m/s | 4.9 |
| 2019 | 21.6°C | 16.0°C | 10.4°C | 29.6°C | 7.1°C | 6 mm | 56% | 3.9 m/s | 5.3 |
| 2018 | 20.4°C | 14.8°C | 9.1°C | 26.8°C | 6.1°C | 3 mm | 55% | 3.6 m/s | 5.5 |
| 2017 | 21.5°C | 16.0°C | 10.6°C | 30.3°C | 7.5°C | 8 mm | 57% | 4.2 m/s | 5.1 |
| 2016 🌧️ | 18.6°C | 14.0°C | 9.3°C | 25.0°C | 6.8°C | 83 mm | 66% | 4.4 m/s | 4.9 |
| 2015 | 19.6°C | 14.6°C | 9.5°C | 27.1°C | 6.7°C | 19 mm | 65% | 3.7 m/s | 5.3 |
| 2014 | 21.3°C | 16.0°C | 10.6°C | 29.1°C | 7.0°C | 21 mm | 63% | 3.8 m/s | 5.5 |
| 2013 | 23.5°C | 18.0°C | 12.4°C | 28.9°C | 8.0°C | 25 mm | 63% | 4.2 m/s | 5 |
| 2012 | 21.1°C | 15.6°C | 10.0°C | 29.4°C | 6.7°C | 10 mm | 60% | 4.3 m/s | 5.2 |
| 2011 | 21.6°C | 16.1°C | 10.6°C | 29.3°C | 7.4°C | 19 mm | 59% | 4.3 m/s | 5.4 |
| 2010 | 17.5°C | 13.4°C | 9.4°C | 22.8°C | 6.7°C | 72 mm | 76% | 3.8 m/s | 4.3 |
| 2009 | 21.1°C | 15.9°C | 10.7°C | 29.6°C | 8.2°C | 51 mm | 61% | 4.6 m/s | 5 |
| 2008 | 21.5°C | 15.7°C | 9.9°C | 32.1°C | 6.2°C | 7 mm | 57% | 3.9 m/s | 5.5 |
| 2007 | 22.1°C | 16.3°C | 10.5°C | 30.7°C | 6.1°C | 15 mm | 55% | 4.1 m/s | 5.4 |
| 2006 | 21.9°C | 16.3°C | 10.7°C | 28.5°C | 7.5°C | 4 mm | 55% | 4.2 m/s | 5.5 |
| 2005 | 20.3°C | 15.4°C | 10.5°C | 27.8°C | 7.8°C | 62 mm | 65% | 4 m/s | 5 |
| 2004 | 19.9°C | 14.8°C | 9.8°C | 28.7°C | 7.0°C | 26 mm | 66% | 3.5 m/s | 4.9 |
| 2003 | 20.2°C | 15.0°C | 9.7°C | 28.5°C | 6.9°C | 17 mm | 64% | 4.3 m/s | 5 |
| 2002 | 20.6°C | 15.2°C | 9.8°C | 28.2°C | 5.5°C | 15 mm | 60% | 4.4 m/s | 5.3 |
| 2001 | 20.6°C | 15.6°C | 10.6°C | 29.1°C | 6.6°C | 80 mm | 66% | 4 m/s | 4.7 |
| 2000 | 21.7°C | 16.3°C | 10.9°C | 29.7°C | 7.9°C | 26 mm | 67% | 3.8 m/s | 5.1 |
| 1999 | 22.2°C | 16.9°C | 11.5°C | 30.1°C | 7.3°C | 23 mm | 61% | 4.1 m/s | 5.1 |
| 1998 | 21.5°C | 16.1°C | 10.8°C | 32.1°C | 8.3°C | 29 mm | 64% | 3.9 m/s | 5.2 |
| 1997 | 19.7°C | 15.1°C | 10.5°C | 23.2°C | 8.0°C | 71 mm | 68% | 3.3 m/s | 4.5 |
| 1996 | 19.5°C | 14.5°C | 9.4°C | 27.8°C | 6.2°C | 58 mm | 65% | 4.7 m/s | 5.1 |
| 1995 | 20.0°C | 14.8°C | 9.7°C | 25.4°C | 5.3°C | 22 mm | 63% | 3.6 m/s | 5 |
| 1994 | 19.2°C | 14.3°C | 9.4°C | 25.1°C | 7.1°C | 11 mm | 63% | 3.8 m/s | 5.5 |
| 1993 | 19.6°C | 14.8°C | 10.0°C | 28.2°C | 6.7°C | 44 mm | 64% | 4 m/s | 5.2 |
| 1992 | 17.2°C | 12.9°C | 8.6°C | 22.8°C | 6.1°C | 81 mm | 71% | 3.8 m/s | 4.9 |
| 1991 | 20.7°C | 15.4°C | 10.1°C | 27.2°C | 6.7°C | 23 mm | 62% | 4.2 m/s | 5.1 |
| 1990 | 20.7°C | 15.2°C | 9.6°C | 30.6°C | 7.4°C | 25 mm | 62% | 4.1 m/s | 5.3 |
| 1989 | 19.5°C | 14.3°C | 9.0°C | 27.2°C | 5.5°C | 16 mm | 66% | 4.2 m/s | 5.4 |
| 1988 | 21.4°C | 16.0°C | 10.6°C | 29.1°C | 6.8°C | 29 mm | 56% | 4.3 m/s | 5.5 |
| 1987 | 20.4°C | 15.2°C | 10.0°C | 29.6°C | 7.1°C | 23 mm | 64% | 3.7 m/s | 5.1 |
| 1986 | 19.1°C | 14.1°C | 9.2°C | 25.6°C | 6.2°C | 27 mm | 67% | 3.9 m/s | 5.2 |
| 1985 | 18.0°C | 13.4°C | 8.7°C | 24.7°C | 5.9°C | 11 mm | 64% | 4.4 m/s | 5.3 |
| 1984 ❄️ | 17.3°C | 12.6°C | 8.0°C | 23.6°C | 5.6°C | 45 mm | 67% | 4.4 m/s | 4.8 |
| 1983 | 20.7°C | 15.3°C | 10.0°C | 28.1°C | 7.1°C | 30 mm | 65% | 4.1 m/s | — |
| 1982 | 19.7°C | 14.8°C | 9.9°C | 28.5°C | 6.9°C | 19 mm | 58% | 3.9 m/s | — |
| 1981 | 22.2°C | 16.4°C | 10.5°C | 29.9°C | 6.9°C | 10 mm | 60% | 3.8 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 20.6°C with lows near 10.1°C (mean 15.4°C), based on 45 years of NASA POWER data.
September averages 28 mm of rainfall in Whyalla, about average for rainfall. The wettest on record was 83 mm in 2016.
The hottest September reached 32.1°C in 1998. The coldest dipped to 5.3°C in 1995.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 1.6°C. Daytime highs moved from 19.6°C to 21.5°C and overnight lows from 9.4°C to 10.8°C over the same span.
September is one of the cooler months of the year in Whyalla and about average for rainfall, so plan for around 20.6°C daytime highs and 10.1°C at night.
Not quite — September is the 4th coolest month in Whyalla, averaging 15.4°C.
For September in Whyalla, pack light layers you can adjust through the day, with typical highs of 20.6°C and lows of 10.1°C.
Relative humidity in September averages 62% — moderately humid.
Average wind speed in September is 4 m/s. The windiest September on record averaged 4.7 m/s (1996).
The wettest September on record was 2016 with 83 mm. On average, September sees 28 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 September, 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 September specifically, along with year-by-year records and how the month has changed over the decades.
