September is one of the cooler months of the year in Colac, with average highs near 14.5°C and lows around 8.2°C (mean 11.4°C). It is a relatively wet time of year, averaging 74 mm of rainfall and 79% relative humidity across the period.
September is one of the cooler months of the year in Colac. Across 45 years of records, the warmest September in Colac was 2023 — when the month averaged 13.7°C — while the coldest was 1992 at 9.5°C. Typical September days reach 14.5°C with nights near 8.2°C. The long-term trend is warming, about 0.3°C per decade.
September is a relatively wet time of year in Colac, averaging 74 mm of rainfall. The wettest September on record was 1996 with 141 mm, while the driest was 2023 at 15 mm.
Relative humidity in Colac during September averages 79%. The most humid September was 1992 at 85%, and the least humid was 2023 at 69%.
September receives about 3.9 kWh/m²/day of solar energy in Colac. The sunniest September was 2023 at 4.5 kWh/m²/day, and the cloudiest were 2009, 2010 and 2024, among others at 3.5.
Average wind speed in Colac during September is 2.6 m/s. The windiest September was 2003 at 3.3 m/s, while the calmest was 1997 at 2 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 11.0°C | 10.8°C | 11.4°C | 11.5°C | 12.2°C | +1.2°C |
| Avg High | 14.2°C | 13.8°C | 14.6°C | 14.6°C | 15.4°C | +1.2°C |
| Avg Low | 7.9°C | 7.8°C | 8.2°C | 8.3°C | 9.0°C | +1.1°C |
| Avg Rain | 73 mm | 89 mm | 83 mm | 66 mm | 51 mm | -22 mm |
September temperatures in Colac have risen by about 1.5°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 4°C (1991) to a record high of 25.5°C (2023).
Rainfall in September is a relatively wet time of year, averaging 74 mm, with a wettest year of 141 mm.
A quieter season to visit Colac
If your dates are flexible, the more temperate months of February and January tend to be the most comfortable for visiting Colac. That said, September — with days averaging 14.5°C and nights around 8.2°C (mean 11.4°C) and moderate rainfall (74 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 | 15.3°C | 12.2°C | 9.2°C | 20.7°C | 5.8°C | 44 mm | 75% | 3 m/s | 3.9 |
| 2024 | 15.3°C | 12.4°C | 9.4°C | 20.3°C | 7.2°C | 44 mm | 73% | 3 m/s | 3.5 |
| 2023 🔥 | 17.8°C | 13.7°C | 9.6°C | 25.5°C | 5.9°C | 15 mm | 69% | 2.4 m/s | 4.5 |
| 2022 | 14.2°C | 11.4°C | 8.6°C | 17.5°C | 5.7°C | 64 mm | 82% | 2.5 m/s | 3.6 |
| 2021 | 14.9°C | 11.7°C | 8.5°C | 21.5°C | 5.9°C | 65 mm | 77% | 2.8 m/s | 3.9 |
| 2020 | 15.2°C | 11.9°C | 8.5°C | 21.4°C | 4.5°C | 71 mm | 76% | 2.7 m/s | 4.1 |
| 2019 | 14.8°C | 11.3°C | 7.9°C | 21.3°C | 5.4°C | 44 mm | 76% | 2.4 m/s | 3.9 |
| 2018 | 14.8°C | 11.2°C | 7.7°C | 20.7°C | 5.3°C | 19 mm | 73% | 2.6 m/s | 4.1 |
| 2017 | 14.2°C | 11.1°C | 7.9°C | 21.3°C | 5.0°C | 61 mm | 76% | 3.1 m/s | 3.7 |
| 2016 | 14.3°C | 11.3°C | 8.3°C | 19.7°C | 6.5°C | 98 mm | 83% | 2.3 m/s | 3.7 |
| 2015 | 15.1°C | 11.7°C | 8.3°C | 23.0°C | 6.2°C | 36 mm | 77% | 2.3 m/s | 4 |
| 2014 | 15.1°C | 12.0°C | 8.8°C | 22.7°C | 6.3°C | 47 mm | 80% | 2.3 m/s | 4.1 |
| 2013 | 15.6°C | 12.6°C | 9.6°C | 19.9°C | 5.9°C | 108 mm | 82% | 2.6 m/s | 3.8 |
| 2012 | 14.4°C | 11.4°C | 8.4°C | 19.0°C | 5.7°C | 85 mm | 80% | 2.6 m/s | 3.9 |
| 2011 | 15.1°C | 11.8°C | 8.5°C | 22.3°C | 6.8°C | 74 mm | 78% | 2.6 m/s | 4.1 |
| 2010 | 13.0°C | 10.5°C | 8.0°C | 15.9°C | 6.0°C | 88 mm | 83% | 2.7 m/s | 3.5 |
| 2009 | 14.5°C | 11.4°C | 8.4°C | 20.2°C | 6.6°C | 113 mm | 80% | 2.8 m/s | 3.5 |
| 2008 | 14.8°C | 11.4°C | 7.9°C | 19.5°C | 5.4°C | 54 mm | 76% | 2.7 m/s | 4 |
| 2007 | 14.8°C | 11.5°C | 8.1°C | 18.7°C | 5.7°C | 78 mm | 77% | 2.8 m/s | 3.9 |
| 2006 | 15.5°C | 11.9°C | 8.3°C | 23.2°C | 5.6°C | 57 mm | 73% | 2.6 m/s | 4.1 |
| 2005 | 14.9°C | 11.8°C | 8.6°C | 21.1°C | 5.1°C | 81 mm | 79% | 2.4 m/s | 3.8 |
| 2004 | 14.1°C | 11.1°C | 8.1°C | 20.0°C | 4.7°C | 84 mm | 84% | 2.3 m/s | 3.6 |
| 2003 | 13.3°C | 10.2°C | 7.1°C | 18.5°C | 4.0°C | 89 mm | 80% | 3.3 m/s | 3.9 |
| 2002 | 14.4°C | 11.1°C | 7.8°C | 21.6°C | 5.3°C | 86 mm | 76% | 3.2 m/s | 3.7 |
| 2001 | 15.7°C | 12.3°C | 9.0°C | 22.4°C | 5.5°C | 60 mm | 80% | 2.3 m/s | 3.7 |
| 2000 | 14.2°C | 11.4°C | 8.7°C | 18.9°C | 6.5°C | 129 mm | 84% | 3.1 m/s | 3.5 |
| 1999 | 16.1°C | 12.6°C | 9.1°C | 22.3°C | 6.0°C | 43 mm | 77% | 2.3 m/s | 3.9 |
| 1998 | 15.3°C | 12.1°C | 8.8°C | 20.2°C | 5.2°C | 78 mm | 79% | 2.6 m/s | 3.8 |
| 1997 | 14.2°C | 11.2°C | 8.1°C | 16.5°C | 6.4°C | 78 mm | 82% | 2 m/s | 4 |
| 1996 🌧️ | 13.1°C | 10.2°C | 7.4°C | 18.9°C | 4.4°C | 141 mm | 82% | 3.2 m/s | 3.7 |
| 1995 | 13.3°C | 10.3°C | 7.3°C | 18.1°C | 4.4°C | 57 mm | 82% | 2.5 m/s | 3.8 |
| 1994 | 12.5°C | 9.6°C | 6.7°C | 17.6°C | 4.8°C | 80 mm | 79% | 2.7 m/s | 3.8 |
| 1993 | 14.2°C | 11.3°C | 8.3°C | 21.7°C | 5.9°C | 113 mm | 83% | 2.4 m/s | 4 |
| 1992 ❄️ | 12.1°C | 9.5°C | 6.9°C | 14.2°C | 4.7°C | 120 mm | 85% | 2.4 m/s | 3.6 |
| 1991 | 13.4°C | 10.3°C | 7.3°C | 18.2°C | 4.0°C | 108 mm | 83% | 2.6 m/s | 3.7 |
| 1990 | 14.1°C | 11.1°C | 8.2°C | 20.0°C | 4.6°C | 74 mm | 81% | 2.5 m/s | 4.1 |
| 1989 | 14.2°C | 10.9°C | 7.7°C | 19.3°C | 5.9°C | 70 mm | 82% | 2.5 m/s | 4.3 |
| 1988 | 15.3°C | 11.8°C | 8.4°C | 19.0°C | 5.9°C | 59 mm | 80% | 2.6 m/s | 3.8 |
| 1987 | 14.9°C | 11.7°C | 8.5°C | 23.8°C | 5.5°C | 59 mm | 81% | 2.5 m/s | 4 |
| 1986 | 13.5°C | 10.6°C | 7.8°C | 19.0°C | 5.8°C | 86 mm | 84% | 2.6 m/s | 3.8 |
| 1985 | 13.7°C | 10.6°C | 7.6°C | 19.9°C | 5.3°C | 40 mm | 80% | 2.4 m/s | 4.3 |
| 1984 | 12.6°C | 9.8°C | 7.0°C | 16.7°C | 5.5°C | 130 mm | 83% | 2.6 m/s | 3.6 |
| 1983 | 13.6°C | 10.7°C | 7.8°C | 19.6°C | 5.6°C | 109 mm | 82% | 2.9 m/s | — |
| 1982 | 14.8°C | 11.1°C | 7.4°C | 22.4°C | 5.6°C | 58 mm | 74% | 2.6 m/s | — |
| 1981 | 15.4°C | 12.0°C | 8.7°C | 21.8°C | 6.1°C | 47 mm | 81% | 2.7 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 14.5°C with lows near 8.2°C (mean 11.4°C), based on 45 years of NASA POWER data.
September averages 74 mm of rainfall in Colac, a relatively wet time of year. The wettest on record was 141 mm in 1996.
The hottest September reached 25.5°C in 2023. The coldest dipped to 4°C in 1991.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 1.5°C. Daytime highs moved from 14°C to 15.5°C and overnight lows from 7.7°C to 9.1°C over the same span.
September is one of the cooler months of the year in Colac and a relatively wet time of year, so plan for around 14.5°C daytime highs and 8.2°C at night.
Not quite — September is the 4th coolest month in Colac, averaging 11.4°C.
For September in Colac, pack light layers you can adjust through the day, with typical highs of 14.5°C and lows of 8.2°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 79% — quite humid.
Average wind speed in September is 2.6 m/s. The windiest September on record averaged 3.3 m/s (2003).
The wettest September on record was 1996 with 141 mm. On average, September sees 74 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 Colac 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.
