September is one of the cooler months of the year in Mount Gambier, with average highs near 14.8°C and lows around 9.3°C (mean 12.1°C). It is a relatively wet time of year, averaging 71 mm of rainfall and 78% relative humidity across the period.
September is one of the cooler months of the year in Mount Gambier. Across 45 years of records, the warmest Septembers in Mount Gambier were 2013 and 2023 — when the month averaged 13.5°C — while the coldest was 1992 at 10.3°C. Typical September days reach 14.8°C with nights near 9.3°C. The long-term trend is warming, about 0.2°C per decade.
September is a relatively wet time of year in Mount Gambier, averaging 71 mm of rainfall. The wettest September on record was 1996 with 141 mm, while the driest was 1987 at 26 mm.
Relative humidity in Mount Gambier during September averages 78%. The most humid September was 2013 at 83%, and the least humid was 1982 at 73%.
September receives about 4.1 kWh/m²/day of solar energy in Mount Gambier. The sunniest September was 2023 at 4.7 kWh/m²/day, and the cloudiest was 2016 at 3.4.
Average wind speed in Mount Gambier during September is 4.2 m/s. The windiest Septembers were 1996 and 2003 at 5.4 m/s, while the calmest was 1997 at 3.1 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 11.8°C | 11.8°C | 12.2°C | 12.1°C | 12.5°C | +0.7°C |
| Avg High | 14.6°C | 14.6°C | 15.0°C | 14.8°C | 15.2°C | +0.6°C |
| Avg Low | 9.0°C | 9.0°C | 9.4°C | 9.3°C | 9.8°C | +0.8°C |
| Avg Rain | 64 mm | 83 mm | 80 mm | 61 mm | 66 mm | +2 mm |
September temperatures in Mount Gambier have risen by about 0.9°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 4°C (2019) to a record high of 24°C (1987).
Rainfall in September is a relatively wet time of year, averaging 71 mm, with a wettest year of 141 mm.
A quieter season to visit Mount Gambier
If your dates are flexible, the more temperate months of February and January tend to be the most comfortable for visiting Mount Gambier. That said, September — with days averaging 14.8°C and nights around 9.3°C (mean 12.1°C) and moderate rainfall (71 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 | 15.1°C | 12.6°C | 10.1°C | 20.4°C | 6.9°C | 69 mm | 76% | 4.8 m/s | 4 |
| 2024 | 14.9°C | 12.8°C | 10.7°C | 19.8°C | 6.4°C | 72 mm | 76% | 5 m/s | 3.8 |
| 2023 | 16.9°C | 13.5°C | 10.1°C | 23.8°C | 7.7°C | 34 mm | 75% | 4 m/s | 4.7 |
| 2022 | 14.2°C | 11.6°C | 8.9°C | 17.9°C | 5.1°C | 68 mm | 81% | 3.7 m/s | 3.8 |
| 2021 | 14.8°C | 12.2°C | 9.6°C | 22.3°C | 6.3°C | 50 mm | 76% | 4.6 m/s | 4.1 |
| 2020 | 15.4°C | 12.3°C | 9.2°C | 21.0°C | 5.2°C | 102 mm | 78% | 4.2 m/s | 4.1 |
| 2019 | 14.5°C | 11.4°C | 8.3°C | 21.3°C | 4.0°C | 52 mm | 77% | 3.7 m/s | 4.3 |
| 2018 | 14.5°C | 11.8°C | 9.0°C | 21.2°C | 5.4°C | 27 mm | 74% | 4.2 m/s | 4.2 |
| 2017 | 14.7°C | 12.2°C | 9.6°C | 21.4°C | 5.2°C | 68 mm | 74% | 4.9 m/s | 4 |
| 2016 | 14.1°C | 11.5°C | 8.9°C | 19.0°C | 6.2°C | 111 mm | 82% | 3.6 m/s | 3.4 |
| 2015 | 15.0°C | 12.0°C | 9.0°C | 22.3°C | 5.8°C | 38 mm | 77% | 3.2 m/s | 4.1 |
| 2014 | 15.6°C | 12.7°C | 9.7°C | 21.8°C | 6.5°C | 35 mm | 76% | 3.9 m/s | 4.6 |
| 2013 🔥 | 16.2°C | 13.5°C | 10.7°C | 20.9°C | 7.4°C | 75 mm | 83% | 4.2 m/s | 3.7 |
| 2012 | 14.9°C | 12.0°C | 9.1°C | 19.6°C | 6.2°C | 58 mm | 78% | 4.2 m/s | 4.2 |
| 2011 | 15.1°C | 12.4°C | 9.7°C | 21.5°C | 6.7°C | 74 mm | 78% | 4 m/s | 4.1 |
| 2010 | 13.3°C | 11.2°C | 9.1°C | 16.3°C | 6.9°C | 72 mm | 80% | 4.1 m/s | 3.5 |
| 2009 | 15.0°C | 12.4°C | 9.7°C | 20.9°C | 7.0°C | 106 mm | 78% | 4.6 m/s | 3.8 |
| 2008 | 15.1°C | 12.1°C | 9.0°C | 21.1°C | 5.0°C | 61 mm | 75% | 4.3 m/s | 4.3 |
| 2007 | 15.4°C | 12.3°C | 9.3°C | 18.6°C | 4.8°C | 74 mm | 76% | 4.6 m/s | 4.2 |
| 2006 | 15.3°C | 12.2°C | 9.1°C | 20.8°C | 5.6°C | 59 mm | 74% | 4.3 m/s | 4.2 |
| 2005 | 15.2°C | 12.4°C | 9.6°C | 21.0°C | 4.9°C | 71 mm | 77% | 3.8 m/s | 4.3 |
| 2004 | 14.4°C | 11.7°C | 9.1°C | 20.8°C | 5.7°C | 67 mm | 82% | 3.4 m/s | 3.8 |
| 2003 | 14.1°C | 11.3°C | 8.6°C | 19.2°C | 5.4°C | 72 mm | 77% | 5.4 m/s | 4.2 |
| 2002 | 14.5°C | 12.0°C | 9.5°C | 22.0°C | 5.5°C | 76 mm | 74% | 5.2 m/s | 3.9 |
| 2001 | 16.2°C | 13.0°C | 9.8°C | 21.6°C | 6.3°C | 89 mm | 80% | 3.8 m/s | 3.8 |
| 2000 | 14.7°C | 12.4°C | 10.1°C | 18.1°C | 7.7°C | 122 mm | 82% | 5.3 m/s | 3.5 |
| 1999 | 16.1°C | 12.9°C | 9.8°C | 23.2°C | 6.9°C | 70 mm | 78% | 3.5 m/s | 4 |
| 1998 | 15.7°C | 12.7°C | 9.7°C | 19.5°C | 5.4°C | 79 mm | 78% | 4.1 m/s | 4 |
| 1997 | 15.0°C | 11.8°C | 8.6°C | 17.3°C | 5.9°C | 90 mm | 82% | 3.1 m/s | 4.1 |
| 1996 🌧️ | 13.7°C | 11.4°C | 9.2°C | 19.1°C | 5.2°C | 141 mm | 79% | 5.4 m/s | 4 |
| 1995 | 14.1°C | 11.4°C | 8.7°C | 18.9°C | 6.0°C | 53 mm | 80% | 3.9 m/s | 4 |
| 1994 | 13.5°C | 11.0°C | 8.5°C | 18.6°C | 4.6°C | 49 mm | 76% | 4.3 m/s | 4.2 |
| 1993 | 15.4°C | 12.1°C | 8.9°C | 21.6°C | 6.2°C | 78 mm | 79% | 3.4 m/s | 4.3 |
| 1992 ❄️ | 12.6°C | 10.3°C | 8.0°C | 14.8°C | 6.6°C | 104 mm | 82% | 3.6 m/s | 3.8 |
| 1991 | 14.5°C | 12.0°C | 9.5°C | 17.8°C | 5.8°C | 83 mm | 81% | 4.2 m/s | 4.1 |
| 1990 | 15.1°C | 12.2°C | 9.3°C | 19.2°C | 6.7°C | 87 mm | 80% | 4 m/s | 4.4 |
| 1989 | 14.6°C | 11.6°C | 8.7°C | 19.6°C | 6.0°C | 60 mm | 82% | 3.9 m/s | 4.2 |
| 1988 | 15.3°C | 12.3°C | 9.3°C | 19.1°C | 6.2°C | 80 mm | 81% | 4 m/s | 4 |
| 1987 | 15.2°C | 12.4°C | 9.7°C | 24.0°C | 7.2°C | 26 mm | 78% | 3.8 m/s | 4.2 |
| 1986 | 14.2°C | 11.7°C | 9.2°C | 19.7°C | 6.3°C | 75 mm | 81% | 4.2 m/s | 4.2 |
| 1985 | 14.2°C | 11.3°C | 8.4°C | 19.1°C | 5.5°C | 31 mm | 77% | 3.8 m/s | 4.6 |
| 1984 | 13.1°C | 10.6°C | 8.1°C | 18.3°C | 5.6°C | 111 mm | 79% | 4.1 m/s | 3.9 |
| 1983 | 14.2°C | 11.7°C | 9.2°C | 20.3°C | 4.2°C | 103 mm | 80% | 4.7 m/s | — |
| 1982 | 14.7°C | 11.6°C | 8.5°C | 20.0°C | 5.9°C | 45 mm | 73% | 4.2 m/s | — |
| 1981 | 15.5°C | 12.7°C | 9.9°C | 21.3°C | 6.8°C | 45 mm | 81% | 4.2 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 9.3°C (mean 12.1°C), based on 45 years of NASA POWER data.
September averages 71 mm of rainfall in Mount Gambier, a relatively wet time of year. The wettest on record was 141 mm in 1996.
The hottest September reached 24°C in 1987. The coldest dipped to 4°C in 2019.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 0.9°C. Daytime highs moved from 14.3°C to 15.2°C and overnight lows from 8.8°C to 9.9°C over the same span.
September is one of the cooler months of the year in Mount Gambier and a relatively wet time of year, so plan for around 14.8°C daytime highs and 9.3°C at night.
Not quite — September is the 4th coolest month in Mount Gambier, averaging 12.1°C.
For September in Mount Gambier, pack light layers you can adjust through the day, with typical highs of 14.8°C and lows of 9.3°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 78% — quite humid.
Average wind speed in September is 4.2 m/s. The windiest September on record averaged 5.4 m/s (1996).
The wettest September on record was 1996 with 141 mm. On average, September sees 71 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 Mount Gambier 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.
