September is one of the cooler months of the year in Yanchep, with average highs near 19.2°C and lows around 12.1°C (mean 15.7°C). It is a relatively wet time of year, averaging 60 mm of rainfall and 74% relative humidity across the period.
September is one of the cooler months of the year in Yanchep. Across 45 years of records, the warmest September in Yanchep was 2023 — when the month averaged 17.7°C — while the coldest was 1992 at 13.8°C. Typical September days reach 19.2°C with nights near 12.1°C. The long-term trend is warming, about 0.2°C per decade.
September is a relatively wet time of year in Yanchep, averaging 60 mm of rainfall. The wettest September on record was 2013 with 119 mm, while the driest was 2019 at 14 mm.
Relative humidity in Yanchep during September averages 74%. The most humid September was 1992 at 79%, and the least humid was 2010 at 65%.
September receives about 5.1 kWh/m²/day of solar energy in Yanchep. The sunniest Septembers were 2015 and 2024 at 5.7 kWh/m²/day, and the cloudiest was 2001 at 4.4.
Average wind speed in Yanchep during September is 4 m/s. The windiest September was 2013 at 4.7 m/s, while the calmest was 1986 at 3.4 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 15.7°C | 15.3°C | 15.2°C | 15.9°C | 16.5°C | +0.8°C |
| Avg High | 19.3°C | 18.6°C | 18.4°C | 19.8°C | 20.4°C | +1.1°C |
| Avg Low | 12.1°C | 12.0°C | 11.9°C | 12.0°C | 12.5°C | +0.4°C |
| Avg Rain | 62 mm | 74 mm | 69 mm | 49 mm | 38 mm | -23 mm |
September temperatures in Yanchep have risen by about 0.8°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 5.5°C (2004) to a record high of 32.1°C (2023).
Rainfall in September is a relatively wet time of year, averaging 60 mm, with a wettest year of 119 mm.
A quieter season to visit Yanchep
If your dates are flexible, the more temperate months of December and April tend to be the most comfortable for visiting Yanchep. That said, September — with days averaging 19.2°C and nights around 12.1°C (mean 15.7°C) and moderate rainfall (60 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 | 19.6°C | 15.9°C | 12.2°C | 26.2°C | 8.2°C | 56 mm | 74% | 3.8 m/s | 5.5 |
| 2024 | 21.4°C | 17.0°C | 12.5°C | 26.6°C | 9.8°C | 15 mm | 69% | 4.1 m/s | 5.7 |
| 2023 🔥 | 21.6°C | 17.7°C | 13.9°C | 32.1°C | 7.3°C | 45 mm | 73% | 4 m/s | 5 |
| 2022 | 19.5°C | 15.8°C | 12.0°C | 26.1°C | 9.3°C | 40 mm | 74% | 3.9 m/s | 5 |
| 2021 | 20.0°C | 15.8°C | 11.5°C | 27.8°C | 8.1°C | 31 mm | 71% | 3.9 m/s | 5.4 |
| 2020 | 20.4°C | 16.6°C | 12.9°C | 27.5°C | 9.5°C | 41 mm | 70% | 4.4 m/s | 5.1 |
| 2019 | 21.7°C | 17.0°C | 12.3°C | 28.8°C | 6.2°C | 14 mm | 73% | 3.5 m/s | 5.6 |
| 2018 | 19.1°C | 15.3°C | 11.6°C | 25.7°C | 6.1°C | 19 mm | 74% | 3.6 m/s | 5.4 |
| 2017 | 19.4°C | 15.8°C | 12.3°C | 26.4°C | 8.0°C | 59 mm | 74% | 3.7 m/s | 5 |
| 2016 | 17.6°C | 14.2°C | 10.8°C | 21.5°C | 7.2°C | 41 mm | 71% | 4 m/s | 5 |
| 2015 | 21.1°C | 16.1°C | 11.2°C | 28.2°C | 6.3°C | 17 mm | 67% | 3.9 m/s | 5.7 |
| 2014 | 20.7°C | 17.1°C | 13.5°C | 28.2°C | 11.1°C | 67 mm | 75% | 4 m/s | 4.8 |
| 2013 🌧️ | 18.4°C | 16.0°C | 13.5°C | 21.3°C | 9.5°C | 119 mm | 77% | 4.7 m/s | 4.6 |
| 2012 | 20.1°C | 15.9°C | 11.7°C | 27.3°C | 8.1°C | 68 mm | 70% | 4.4 m/s | 5.3 |
| 2011 | 19.1°C | 15.6°C | 12.1°C | 21.7°C | 8.7°C | 73 mm | 74% | 4 m/s | 4.9 |
| 2010 | 20.8°C | 15.9°C | 11.0°C | 28.0°C | 7.6°C | 17 mm | 65% | 3.8 m/s | 5.5 |
| 2009 | 17.3°C | 14.5°C | 11.7°C | 22.7°C | 7.3°C | 89 mm | 75% | 4.5 m/s | 4.5 |
| 2008 | 18.7°C | 15.3°C | 12.0°C | 23.0°C | 7.4°C | 74 mm | 75% | 4.2 m/s | 4.9 |
| 2007 | 18.5°C | 15.4°C | 12.3°C | 23.5°C | 8.2°C | 75 mm | 77% | 3.9 m/s | 4.9 |
| 2006 | 19.5°C | 15.9°C | 12.4°C | 27.5°C | 8.2°C | 54 mm | 74% | 4.2 m/s | 5 |
| 2005 | 17.6°C | 14.6°C | 11.5°C | 22.0°C | 6.6°C | 88 mm | 75% | 4.4 m/s | 4.9 |
| 2004 | 18.3°C | 14.4°C | 10.4°C | 22.0°C | 5.5°C | 39 mm | 75% | 3.8 m/s | 5.2 |
| 2003 | 18.0°C | 14.8°C | 11.6°C | 25.1°C | 8.6°C | 94 mm | 76% | 4.3 m/s | 5 |
| 2002 | 18.5°C | 15.1°C | 11.7°C | 25.2°C | 7.8°C | 49 mm | 73% | 4.1 m/s | 5.1 |
| 2001 | 18.2°C | 15.3°C | 12.4°C | 23.1°C | 9.8°C | 95 mm | 76% | 3.8 m/s | 4.4 |
| 2000 | 19.4°C | 16.3°C | 13.1°C | 24.1°C | 10.3°C | 32 mm | 77% | 3.6 m/s | 5 |
| 1999 | 18.7°C | 15.1°C | 11.4°C | 26.1°C | 7.4°C | 110 mm | 78% | 4.1 m/s | 4.8 |
| 1998 | 18.2°C | 14.8°C | 11.5°C | 22.1°C | 7.8°C | 92 mm | 74% | 4.4 m/s | 4.9 |
| 1997 | 18.8°C | 15.6°C | 12.5°C | 23.2°C | 10.4°C | 71 mm | 78% | 3.5 m/s | 5 |
| 1996 | 18.6°C | 15.9°C | 13.1°C | 21.3°C | 7.9°C | 110 mm | 74% | 4.6 m/s | 4.9 |
| 1995 | 18.8°C | 15.9°C | 12.9°C | 23.5°C | 9.7°C | 59 mm | 76% | 3.5 m/s | 5 |
| 1994 | 20.3°C | 16.0°C | 11.8°C | 26.1°C | 8.0°C | 41 mm | 72% | 4.2 m/s | 5.4 |
| 1993 | 18.4°C | 14.8°C | 11.3°C | 24.3°C | 8.3°C | 80 mm | 75% | 3.8 m/s | 5.1 |
| 1992 ❄️ | 16.5°C | 13.8°C | 11.1°C | 22.7°C | 7.8°C | 59 mm | 79% | 4.3 m/s | 4.7 |
| 1991 | 18.3°C | 15.4°C | 12.5°C | 22.9°C | 9.0°C | 68 mm | 77% | 3.8 m/s | 4.9 |
| 1990 | 19.7°C | 15.5°C | 11.4°C | 27.7°C | 7.4°C | 49 mm | 72% | 3.6 m/s | 5.1 |
| 1989 | 19.2°C | 16.0°C | 12.8°C | 23.4°C | 8.7°C | 51 mm | 73% | 4 m/s | 4.9 |
| 1988 | 19.3°C | 16.3°C | 13.3°C | 25.4°C | 9.8°C | 64 mm | 75% | 4.1 m/s | 4.9 |
| 1987 | 20.4°C | 15.9°C | 11.4°C | 25.7°C | 8.0°C | 39 mm | 75% | 3.8 m/s | 5.4 |
| 1986 | 18.6°C | 15.4°C | 12.2°C | 25.1°C | 8.7°C | 45 mm | 77% | 3.4 m/s | 4.6 |
| 1985 | 19.9°C | 15.6°C | 11.3°C | 26.4°C | 6.7°C | 74 mm | 73% | 4 m/s | 5 |
| 1984 | 18.8°C | 15.0°C | 11.3°C | 21.5°C | 7.5°C | 71 mm | 72% | 4.1 m/s | 5.3 |
| 1983 | 19.5°C | 16.3°C | 13.1°C | 25.3°C | 9.1°C | 82 mm | 77% | 4.1 m/s | — |
| 1982 | 19.2°C | 15.4°C | 11.5°C | 27.1°C | 6.9°C | 82 mm | 75% | 3.9 m/s | — |
| 1981 | 19.0°C | 15.5°C | 12.0°C | 23.4°C | 6.6°C | 45 mm | 77% | 3.7 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 19.2°C with lows near 12.1°C (mean 15.7°C), based on 45 years of NASA POWER data.
September averages 60 mm of rainfall in Yanchep, a relatively wet time of year. The wettest on record was 119 mm in 2013.
The hottest September reached 32.1°C in 2023. The coldest dipped to 5.5°C in 2004.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 0.8°C. Daytime highs moved from 19.3°C to 20.4°C and overnight lows from 11.8°C to 12.4°C over the same span.
September is one of the cooler months of the year in Yanchep and a relatively wet time of year, so plan for around 19.2°C daytime highs and 12.1°C at night.
Not quite — September is the 3rd coolest month in Yanchep, averaging 15.7°C.
For September in Yanchep, pack light layers you can adjust through the day, with typical highs of 19.2°C and lows of 12.1°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 74% — moderately humid.
Average wind speed in September is 4 m/s. The windiest September on record averaged 4.7 m/s (2013).
The wettest September on record was 2013 with 119 mm. On average, September sees 60 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 Yanchep 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.
