September is one of the cooler months of the year in Mount Barker, with average highs near 16.7°C and lows around 6.7°C (mean 11.7°C). It is a relatively wet time of year, averaging 67 mm of rainfall and 82% relative humidity across the period.
September is one of the cooler months of the year in Mount Barker. Across 45 years of records, the warmest Septembers in Mount Barker were 2019 and 2023 — when the month averaged 13.4°C — while the coldest was 1992 at 9.3°C. Typical September days reach 16.7°C with nights near 6.7°C. The long-term September temperature trend is broadly flat.
September is a relatively wet time of year in Mount Barker, averaging 67 mm of rainfall. The wettest September on record was 2013 with 141 mm, while the driest was 2004 at 34 mm.
Relative humidity in Mount Barker during September averages 82%. The most humid September was 1992 at 87%, and the least humid was 1982 at 78%.
September receives about 4.4 kWh/m²/day of solar energy in Mount Barker. The sunniest Septembers were 1987, 2019 and 2023 at 4.7 kWh/m²/day, and the cloudiest were 1995 and 2001 at 4.
Average wind speed in Mount Barker during September is 3.3 m/s. The windiest September was 2013 at 4.5 m/s, while the calmest was 1982 at 2.6 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 11.9°C | 11.2°C | 11.4°C | 11.9°C | 12.3°C | +0.4°C |
| Avg High | 17.1°C | 16.1°C | 16.1°C | 17.0°C | 17.3°C | +0.2°C |
| Avg Low | 6.7°C | 6.4°C | 6.6°C | 6.8°C | 7.3°C | +0.6°C |
| Avg Rain | 57 mm | 74 mm | 72 mm | 69 mm | 58 mm | +1 mm |
September temperatures in Mount Barker have risen by about 0.5°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 1°C (2019) to a record high of 28.9°C (2006).
Rainfall in September is a relatively wet time of year, averaging 67 mm, with a wettest year of 141 mm.
A quieter season to visit Mount Barker
If your dates are flexible, the more temperate months of February and January tend to be the most comfortable for visiting Mount Barker. That said, September — with days averaging 16.7°C and nights around 6.7°C (mean 11.7°C) and moderate rainfall (67 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 | 16.8°C | 12.0°C | 7.2°C | 25.2°C | 4.3°C | 74 mm | 84% | 3.1 m/s | 4.6 |
| 2024 | 17.4°C | 12.3°C | 7.3°C | 24.2°C | 4.3°C | 38 mm | 82% | 2.8 m/s | 4.6 |
| 2023 | 18.7°C | 13.4°C | 8.2°C | 26.8°C | 3.5°C | 59 mm | 82% | 3.3 m/s | 4.7 |
| 2022 | 17.1°C | 12.2°C | 7.4°C | 23.7°C | 3.7°C | 37 mm | 81% | 3 m/s | 4.6 |
| 2021 | 16.9°C | 11.7°C | 6.5°C | 23.8°C | 4.5°C | 72 mm | 82% | 3 m/s | 4.4 |
| 2020 | 16.7°C | 11.9°C | 7.2°C | 21.7°C | 3.5°C | 65 mm | 83% | 3.6 m/s | 4.5 |
| 2019 🔥 | 19.2°C | 13.4°C | 7.7°C | 27.1°C | 1.0°C | 44 mm | 80% | 2.9 m/s | 4.7 |
| 2018 | 16.5°C | 11.5°C | 6.6°C | 24.0°C | 2.7°C | 38 mm | 83% | 3.2 m/s | 4.5 |
| 2017 | 16.4°C | 11.8°C | 7.2°C | 21.6°C | 2.3°C | 100 mm | 83% | 3.1 m/s | 4.3 |
| 2016 | 14.4°C | 9.6°C | 4.8°C | 18.3°C | 2.1°C | 81 mm | 85% | 3.2 m/s | 4.2 |
| 2015 | 17.8°C | 12.1°C | 6.4°C | 26.1°C | 3.3°C | 40 mm | 79% | 2.9 m/s | 4.6 |
| 2014 | 18.7°C | 13.2°C | 7.7°C | 26.2°C | 3.7°C | 57 mm | 81% | 3.3 m/s | 4.5 |
| 2013 🌧️ | 16.2°C | 12.1°C | 8.0°C | 20.7°C | 4.9°C | 141 mm | 84% | 4.5 m/s | 4.2 |
| 2012 | 17.3°C | 12.1°C | 6.8°C | 23.9°C | 3.5°C | 85 mm | 81% | 3.5 m/s | 4.5 |
| 2011 | 16.4°C | 11.6°C | 6.8°C | 20.7°C | 4.5°C | 73 mm | 82% | 3.4 m/s | 4.5 |
| 2010 | 17.1°C | 11.5°C | 6.0°C | 23.9°C | 3.2°C | 35 mm | 79% | 2.8 m/s | 4.6 |
| 2009 | 14.3°C | 10.0°C | 5.6°C | 19.6°C | 1.6°C | 100 mm | 83% | 4.3 m/s | 4.2 |
| 2008 | 16.3°C | 11.6°C | 7.0°C | 22.7°C | 2.8°C | 72 mm | 81% | 3.4 m/s | 4.2 |
| 2007 | 16.5°C | 11.6°C | 6.7°C | 21.0°C | 3.0°C | 92 mm | 84% | 3.7 m/s | 4.4 |
| 2006 | 17.7°C | 12.6°C | 7.5°C | 28.9°C | 3.3°C | 36 mm | 79% | 3.7 m/s | 4.4 |
| 2005 | 15.3°C | 10.5°C | 5.7°C | 20.0°C | 1.9°C | 80 mm | 83% | 3.8 m/s | 4.3 |
| 2004 | 16.4°C | 11.2°C | 6.1°C | 19.6°C | 2.4°C | 34 mm | 80% | 2.7 m/s | 4.4 |
| 2003 | 15.5°C | 11.1°C | 6.6°C | 22.3°C | 3.9°C | 126 mm | 84% | 4 m/s | 4.2 |
| 2002 | 16.0°C | 11.4°C | 6.8°C | 23.2°C | 3.5°C | 57 mm | 82% | 3.6 m/s | 4.3 |
| 2001 | 16.3°C | 11.6°C | 6.8°C | 25.6°C | 3.4°C | 83 mm | 83% | 3.5 m/s | 4 |
| 2000 | 17.1°C | 12.2°C | 7.2°C | 22.2°C | 3.4°C | 37 mm | 83% | 3.4 m/s | 4.4 |
| 1999 | 16.6°C | 11.4°C | 6.3°C | 24.9°C | 1.4°C | 92 mm | 83% | 3.2 m/s | 4.2 |
| 1998 | 15.2°C | 10.7°C | 6.2°C | 20.2°C | 2.7°C | 87 mm | 83% | 3.5 m/s | 4.2 |
| 1997 | 16.3°C | 11.7°C | 7.1°C | 22.8°C | 2.2°C | 86 mm | 85% | 2.9 m/s | 4.1 |
| 1996 | 15.6°C | 11.2°C | 6.8°C | 19.5°C | 3.8°C | 121 mm | 83% | 4.1 m/s | 4.3 |
| 1995 | 16.1°C | 11.7°C | 7.2°C | 22.2°C | 4.2°C | 77 mm | 85% | 3 m/s | 4 |
| 1994 | 17.5°C | 11.8°C | 6.2°C | 24.7°C | 2.0°C | 44 mm | 80% | 3 m/s | 4.5 |
| 1993 | 16.3°C | 11.1°C | 5.8°C | 22.7°C | 2.1°C | 48 mm | 83% | 3.2 m/s | 4.5 |
| 1992 ❄️ | 13.2°C | 9.3°C | 5.5°C | 21.0°C | 1.9°C | 85 mm | 87% | 3.1 m/s | 4.1 |
| 1991 | 16.6°C | 11.7°C | 6.9°C | 24.5°C | 2.4°C | 58 mm | 85% | 3.1 m/s | 4.3 |
| 1990 | 17.5°C | 11.7°C | 5.8°C | 25.5°C | 2.9°C | 46 mm | 82% | 2.7 m/s | 4.4 |
| 1989 | 16.6°C | 11.7°C | 6.9°C | 20.9°C | 3.7°C | 51 mm | 82% | 3.7 m/s | 4.5 |
| 1988 | 16.7°C | 11.8°C | 6.9°C | 23.0°C | 4.6°C | 66 mm | 84% | 3.8 m/s | 4.4 |
| 1987 | 18.9°C | 13.0°C | 7.1°C | 26.4°C | 3.5°C | 36 mm | 78% | 2.7 m/s | 4.7 |
| 1986 | 16.5°C | 11.5°C | 6.6°C | 26.4°C | 2.8°C | 77 mm | 84% | 3.1 m/s | 4.2 |
| 1985 | 17.4°C | 12.0°C | 6.6°C | 23.6°C | 1.9°C | 53 mm | 80% | 2.8 m/s | 4.6 |
| 1984 | 15.0°C | 10.4°C | 5.7°C | 18.6°C | 2.0°C | 74 mm | 84% | 2.9 m/s | 4.5 |
| 1983 | 17.7°C | 12.8°C | 7.8°C | 25.3°C | 4.5°C | 76 mm | 84% | 3.5 m/s | — |
| 1982 | 17.9°C | 12.0°C | 6.0°C | 26.5°C | 1.6°C | 43 mm | 78% | 2.6 m/s | — |
| 1981 | 17.5°C | 12.0°C | 6.5°C | 26.5°C | 1.9°C | 37 mm | 81% | 3.5 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 16.7°C with lows near 6.7°C (mean 11.7°C), based on 45 years of NASA POWER data.
September averages 67 mm of rainfall in Mount Barker, a relatively wet time of year. The wettest on record was 141 mm in 2013.
The hottest September reached 28.9°C in 2006. The coldest dipped to 1°C in 2019.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 0.5°C. Daytime highs moved from 17.1°C to 17.4°C and overnight lows from 6.5°C to 7.3°C over the same span.
September is one of the cooler months of the year in Mount Barker and a relatively wet time of year, so plan for around 16.7°C daytime highs and 6.7°C at night.
Not quite — September is the 4th coolest month in Mount Barker, averaging 11.7°C.
For September in Mount Barker, pack warm layers and a jacket for chilly mornings, with typical highs of 16.7°C and lows of 6.7°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 82% — quite humid.
Average wind speed in September is 3.3 m/s. The windiest September on record averaged 4.5 m/s (2013).
The wettest September on record was 2013 with 141 mm. On average, September sees 67 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 Barker 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.
