September is one of the cooler months of the year in Wonthaggi, with average highs near 14.8°C and lows around 8.9°C (mean 11.9°C). It is a relatively wet time of year, averaging 86 mm of rainfall and 78% relative humidity across the period.
September is one of the cooler months of the year in Wonthaggi. Across 45 years of records, the warmest September in Wonthaggi was 2023 — when the month averaged 14°C — while the coldest was 1992 at 9.8°C. Typical September days reach 14.8°C with nights near 8.9°C. The long-term trend is warming, about 0.4°C per decade.
September is a relatively wet time of year in Wonthaggi, averaging 86 mm of rainfall. The wettest September on record was 1993 with 180 mm, while the driest was 2015 at 27 mm.
Relative humidity in Wonthaggi during September averages 78%. The most humid September was 1992 at 85%, and the least humid was 2023 at 69%.
September receives about 4 kWh/m²/day of solar energy in Wonthaggi. The sunniest Septembers were 1985, 2018 and 2023 at 4.4 kWh/m²/day, and the cloudiest was 1992 at 3.5.
Average wind speed in Wonthaggi during September is 1.7 m/s. The windiest September was 2003 at 2.2 m/s, while the calmest was 1997 at 1.3 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 11.4°C | 11.2°C | 12.1°C | 12.1°C | 12.7°C | +1.3°C |
| Avg High | 14.3°C | 14.0°C | 15.1°C | 15.0°C | 15.8°C | +1.5°C |
| Avg Low | 8.5°C | 8.4°C | 9.1°C | 9.1°C | 9.7°C | +1.2°C |
| Avg Rain | 86 mm | 108 mm | 89 mm | 74 mm | 68 mm | -18 mm |
September temperatures in Wonthaggi have risen by about 1.6°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 4.3°C (1983) to a record high of 24.9°C (2023).
Rainfall in September is a relatively wet time of year, averaging 86 mm, with a wettest year of 180 mm.
A quieter season to visit Wonthaggi
If your dates are flexible, the more temperate months of February and January tend to be the most comfortable for visiting Wonthaggi. That said, September — with days averaging 14.8°C and nights around 8.9°C (mean 11.9°C) and higher rainfall (86 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 | 15.8°C | 13.0°C | 10.2°C | 21.0°C | 4.9°C | 45 mm | 71% | 1.9 m/s | 3.8 |
| 2024 | 15.8°C | 13.0°C | 10.2°C | 21.1°C | 7.0°C | 76 mm | 72% | 2 m/s | 3.7 |
| 2023 🔥 | 18.0°C | 14.0°C | 10.1°C | 24.9°C | 6.7°C | 36 mm | 69% | 1.4 m/s | 4.4 |
| 2022 | 14.7°C | 12.0°C | 9.2°C | 18.3°C | 4.6°C | 58 mm | 81% | 1.5 m/s | 3.8 |
| 2021 | 15.3°C | 12.2°C | 9.1°C | 21.1°C | 5.4°C | 125 mm | 76% | 1.8 m/s | 4.1 |
| 2020 | 15.4°C | 12.2°C | 9.1°C | 23.0°C | 5.6°C | 67 mm | 75% | 1.6 m/s | 4.1 |
| 2019 | 15.1°C | 12.0°C | 8.9°C | 21.3°C | 6.4°C | 73 mm | 76% | 1.7 m/s | 4.1 |
| 2018 | 15.3°C | 11.7°C | 8.2°C | 20.6°C | 5.5°C | 36 mm | 71% | 1.6 m/s | 4.4 |
| 2017 | 14.8°C | 11.9°C | 9.0°C | 24.5°C | 5.1°C | 79 mm | 73% | 2.1 m/s | 3.9 |
| 2016 | 14.9°C | 12.0°C | 9.1°C | 20.0°C | 7.1°C | 65 mm | 80% | 1.4 m/s | 3.9 |
| 2015 | 15.2°C | 11.9°C | 8.6°C | 22.4°C | 6.3°C | 27 mm | 75% | 1.5 m/s | 4.2 |
| 2014 | 15.6°C | 12.5°C | 9.5°C | 21.3°C | 6.2°C | 75 mm | 78% | 1.5 m/s | 4.3 |
| 2013 | 15.9°C | 13.1°C | 10.4°C | 19.8°C | 5.3°C | 121 mm | 81% | 1.7 m/s | 3.9 |
| 2012 | 14.5°C | 11.9°C | 9.3°C | 19.7°C | 5.5°C | 98 mm | 80% | 1.7 m/s | 3.9 |
| 2011 | 15.5°C | 12.4°C | 9.3°C | 21.6°C | 6.8°C | 85 mm | 76% | 1.7 m/s | 4.2 |
| 2010 | 13.2°C | 11.1°C | 8.9°C | 16.8°C | 5.7°C | 82 mm | 80% | 1.9 m/s | 3.7 |
| 2009 | 15.3°C | 12.3°C | 9.3°C | 21.5°C | 6.8°C | 123 mm | 77% | 1.8 m/s | 3.8 |
| 2008 | 15.7°C | 12.4°C | 9.1°C | 20.7°C | 6.7°C | 45 mm | 70% | 1.7 m/s | 4.3 |
| 2007 | 15.0°C | 11.9°C | 8.7°C | 17.6°C | 5.0°C | 82 mm | 76% | 1.8 m/s | 4.1 |
| 2006 | 16.2°C | 12.6°C | 9.0°C | 23.6°C | 5.6°C | 55 mm | 72% | 1.6 m/s | 4.2 |
| 2005 | 15.1°C | 12.3°C | 9.4°C | 20.8°C | 6.0°C | 98 mm | 80% | 1.5 m/s | 4 |
| 2004 | 14.2°C | 11.5°C | 8.9°C | 19.3°C | 6.1°C | 111 mm | 84% | 1.6 m/s | 3.7 |
| 2003 | 13.7°C | 11.1°C | 8.4°C | 18.7°C | 5.5°C | 92 mm | 77% | 2.2 m/s | 4 |
| 2002 | 15.3°C | 12.1°C | 9.0°C | 21.6°C | 6.6°C | 91 mm | 72% | 2.1 m/s | 4 |
| 2001 | 16.1°C | 12.8°C | 9.6°C | 21.4°C | 6.1°C | 47 mm | 79% | 1.4 m/s | 3.8 |
| 2000 | 14.7°C | 12.2°C | 9.7°C | 18.3°C | 6.9°C | 141 mm | 81% | 2.1 m/s | 4 |
| 1999 | 16.0°C | 12.7°C | 9.4°C | 22.6°C | 5.5°C | 65 mm | 78% | 1.4 m/s | 4 |
| 1998 | 15.9°C | 12.9°C | 9.9°C | 21.5°C | 6.4°C | 77 mm | 77% | 1.6 m/s | 4 |
| 1997 | 14.5°C | 11.5°C | 8.5°C | 16.9°C | 5.4°C | 66 mm | 82% | 1.3 m/s | 4.2 |
| 1996 | 13.5°C | 10.7°C | 8.0°C | 18.6°C | 5.8°C | 156 mm | 82% | 2.1 m/s | 3.8 |
| 1995 | 13.6°C | 10.5°C | 7.4°C | 19.0°C | 4.9°C | 67 mm | 82% | 1.6 m/s | 4.1 |
| 1994 | 12.7°C | 10.2°C | 7.7°C | 18.5°C | 4.8°C | 107 mm | 77% | 1.9 m/s | 3.8 |
| 1993 🌧️ | 14.1°C | 11.4°C | 8.7°C | 20.8°C | 5.9°C | 180 mm | 84% | 1.5 m/s | 4 |
| 1992 ❄️ | 12.2°C | 9.8°C | 7.4°C | 14.7°C | 4.4°C | 148 mm | 85% | 1.7 m/s | 3.5 |
| 1991 | 13.2°C | 10.6°C | 8.1°C | 18.5°C | 5.7°C | 136 mm | 84% | 1.8 m/s | 3.8 |
| 1990 | 14.4°C | 11.4°C | 8.5°C | 19.6°C | 4.5°C | 80 mm | 82% | 1.6 m/s | 4.1 |
| 1989 | 14.2°C | 11.2°C | 8.2°C | 19.6°C | 4.9°C | 74 mm | 83% | 1.6 m/s | 4.3 |
| 1988 | 15.5°C | 12.4°C | 9.2°C | 19.7°C | 5.9°C | 91 mm | 79% | 1.7 m/s | 4 |
| 1987 | 14.8°C | 12.1°C | 9.4°C | 23.1°C | 7.3°C | 68 mm | 81% | 1.7 m/s | 4.1 |
| 1986 | 13.7°C | 11.0°C | 8.3°C | 19.9°C | 6.1°C | 79 mm | 83% | 1.7 m/s | 3.9 |
| 1985 | 13.7°C | 11.0°C | 8.2°C | 19.9°C | 6.0°C | 45 mm | 81% | 1.5 m/s | 4.4 |
| 1984 | 13.0°C | 10.5°C | 8.0°C | 17.2°C | 6.2°C | 132 mm | 84% | 1.7 m/s | 4 |
| 1983 | 13.9°C | 11.1°C | 8.3°C | 18.5°C | 4.3°C | 142 mm | 82% | 1.8 m/s | — |
| 1982 | 14.6°C | 11.2°C | 7.8°C | 19.7°C | 5.0°C | 89 mm | 74% | 1.7 m/s | — |
| 1981 | 15.1°C | 12.1°C | 9.1°C | 21.7°C | 6.4°C | 56 mm | 81% | 1.7 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 14.8°C with lows near 8.9°C (mean 11.9°C), based on 45 years of NASA POWER data.
September averages 86 mm of rainfall in Wonthaggi, a relatively wet time of year. The wettest on record was 180 mm in 1993.
The hottest September reached 24.9°C in 2023. The coldest dipped to 4.3°C in 1983.
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 14.1°C to 15.9°C and overnight lows from 8.3°C to 9.8°C over the same span.
September is one of the cooler months of the year in Wonthaggi and a relatively wet time of year, so plan for around 14.8°C daytime highs and 8.9°C at night.
Not quite — September is the 4th coolest month in Wonthaggi, averaging 11.9°C.
For September in Wonthaggi, pack light layers you can adjust through the day, with typical highs of 14.8°C and lows of 8.9°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 78% — quite humid.
Average wind speed in September is 1.7 m/s. The windiest September on record averaged 2.2 m/s (2003).
The wettest September on record was 1993 with 180 mm. On average, September sees 86 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 Wonthaggi 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.
