September is one of the cooler months of the year in Port Denison, with average highs near 21.2°C and lows around 12.6°C (mean 16.9°C). It is about average for rainfall, averaging 37 mm of rainfall and 70% relative humidity across the period.
September is one of the cooler months of the year in Port Denison. Across 45 years of records, the warmest September in Port Denison was 2023 — when the month averaged 19°C — while the coldest was 2016 at 15.1°C. Typical September days reach 21.2°C with nights near 12.6°C. The long-term trend is warming, about 0.2°C per decade.
September is about average for rainfall in Port Denison, averaging 37 mm of rainfall. The wettest September on record was 2014 with 71 mm, while the driest was 2020 at 7 mm.
Relative humidity in Port Denison during September averages 70%. The most humid September was 1992 at 77%, and the least humid was 2010 at 61%.
September receives about 5.5 kWh/m²/day of solar energy in Port Denison. The sunniest September was 2024 at 6.1 kWh/m²/day, and the cloudiest were 1992 and 2014 at 5.
Average wind speed in Port Denison during September is 4 m/s. The windiest September was 2012 at 4.5 m/s, while the calmest was 1986 at 3.3 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 17.0°C | 16.4°C | 16.5°C | 17.2°C | 17.9°C | +0.9°C |
| Avg High | 21.3°C | 20.5°C | 20.6°C | 21.8°C | 22.5°C | +1.2°C |
| Avg Low | 12.6°C | 12.4°C | 12.3°C | 12.6°C | 13.3°C | +0.7°C |
| Avg Rain | 37 mm | 47 mm | 43 mm | 32 mm | 18 mm | -19 mm |
September temperatures in Port Denison have risen by about 0.9°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 6.8°C (2004) to a record high of 33.6°C (2023).
Rainfall in September is about average for rainfall, averaging 37 mm, with a wettest year of 71 mm.
A quieter season to visit Port Denison
If your dates are flexible, the more temperate months of November and April tend to be the most comfortable for visiting Port Denison. That said, September — with days averaging 21.2°C and nights around 12.6°C (mean 16.9°C) and moderate rainfall (37 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 | 21.7°C | 17.1°C | 12.5°C | 29.0°C | 8.3°C | 30 mm | 67% | 4.1 m/s | 5.8 |
| 2024 | 23.7°C | 18.6°C | 13.5°C | 27.7°C | 11.3°C | 8 mm | 63% | 4.4 m/s | 6.1 |
| 2023 🔥 | 23.4°C | 19.0°C | 14.7°C | 33.6°C | 9.9°C | 16 mm | 69% | 3.9 m/s | 5.4 |
| 2022 | 21.2°C | 17.0°C | 12.7°C | 28.2°C | 9.6°C | 39 mm | 70% | 3.9 m/s | 5.4 |
| 2021 | 22.5°C | 17.5°C | 12.6°C | 29.4°C | 9.0°C | 10 mm | 63% | 4.1 m/s | 5.8 |
| 2020 | 22.5°C | 18.0°C | 13.5°C | 29.5°C | 10.9°C | 7 mm | 65% | 4 m/s | 5.7 |
| 2019 | 23.6°C | 18.3°C | 13.0°C | 29.8°C | 9.0°C | 7 mm | 67% | 3.7 m/s | 6 |
| 2018 | 21.5°C | 16.7°C | 12.0°C | 27.9°C | 8.4°C | 7 mm | 69% | 3.8 m/s | 5.6 |
| 2017 | 21.5°C | 17.3°C | 13.1°C | 27.9°C | 8.9°C | 40 mm | 70% | 3.9 m/s | 5.4 |
| 2016 ❄️ | 19.5°C | 15.1°C | 10.7°C | 23.8°C | 8.2°C | 15 mm | 69% | 4 m/s | 5.6 |
| 2015 | 23.4°C | 17.9°C | 12.4°C | 30.9°C | 7.5°C | 13 mm | 62% | 3.9 m/s | 5.9 |
| 2014 🌧️ | 22.8°C | 18.5°C | 14.1°C | 28.1°C | 10.4°C | 71 mm | 71% | 4 m/s | 5 |
| 2013 | 20.2°C | 17.0°C | 13.7°C | 24.5°C | 9.8°C | 63 mm | 74% | 4.4 m/s | 5.2 |
| 2012 | 21.9°C | 17.4°C | 12.8°C | 30.1°C | 9.3°C | 45 mm | 67% | 4.5 m/s | 5.4 |
| 2011 | 21.0°C | 16.8°C | 12.5°C | 26.3°C | 8.9°C | 45 mm | 70% | 3.8 m/s | 5.4 |
| 2010 | 22.7°C | 17.3°C | 12.0°C | 32.4°C | 8.5°C | 10 mm | 61% | 3.9 m/s | 5.9 |
| 2009 | 19.2°C | 15.5°C | 11.9°C | 25.8°C | 8.4°C | 52 mm | 72% | 4 m/s | 5.2 |
| 2008 | 21.0°C | 16.7°C | 12.4°C | 24.2°C | 7.8°C | 49 mm | 70% | 4.1 m/s | 5.1 |
| 2007 | 21.0°C | 16.9°C | 12.7°C | 26.6°C | 9.7°C | 32 mm | 71% | 3.9 m/s | 5.3 |
| 2006 | 22.2°C | 17.7°C | 13.2°C | 28.1°C | 8.6°C | 24 mm | 69% | 4.3 m/s | 5.4 |
| 2005 | 19.7°C | 15.8°C | 12.0°C | 24.5°C | 7.5°C | 49 mm | 72% | 4.4 m/s | 5.3 |
| 2004 | 20.4°C | 15.9°C | 11.4°C | 24.4°C | 6.8°C | 42 mm | 70% | 4 m/s | 5.3 |
| 2003 | 19.3°C | 15.8°C | 12.2°C | 25.6°C | 9.6°C | 62 mm | 74% | 4.1 m/s | 5.4 |
| 2002 | 21.0°C | 16.5°C | 12.0°C | 27.6°C | 7.5°C | 30 mm | 67% | 4.3 m/s | 5.5 |
| 2001 | 20.3°C | 16.3°C | 12.2°C | 26.7°C | 8.5°C | 61 mm | 73% | 3.8 m/s | 5.2 |
| 2000 | 21.9°C | 17.5°C | 13.1°C | 26.6°C | 11.0°C | 25 mm | 72% | 3.8 m/s | 5.4 |
| 1999 | 19.9°C | 15.9°C | 11.9°C | 26.1°C | 8.2°C | 60 mm | 76% | 4.1 m/s | 5.5 |
| 1998 | 20.0°C | 16.1°C | 12.1°C | 23.8°C | 7.7°C | 48 mm | 70% | 4.4 m/s | 5.4 |
| 1997 | 20.2°C | 16.4°C | 12.5°C | 24.2°C | 9.3°C | 59 mm | 76% | 3.6 m/s | 5.7 |
| 1996 | 20.0°C | 16.7°C | 13.4°C | 22.7°C | 9.3°C | 54 mm | 74% | 4.3 m/s | 5.3 |
| 1995 | 21.1°C | 16.9°C | 12.8°C | 26.8°C | 8.9°C | 46 mm | 73% | 3.8 m/s | 5.6 |
| 1994 | 23.0°C | 18.0°C | 13.0°C | 29.4°C | 8.6°C | 22 mm | 67% | 4.2 m/s | 5.8 |
| 1993 | 20.0°C | 15.8°C | 11.7°C | 25.3°C | 8.7°C | 44 mm | 71% | 3.8 m/s | 5.7 |
| 1992 | 18.6°C | 15.2°C | 11.8°C | 23.3°C | 8.8°C | 61 mm | 77% | 4 m/s | 5 |
| 1991 | 20.2°C | 16.4°C | 12.6°C | 26.0°C | 8.4°C | 39 mm | 74% | 3.7 m/s | 5.4 |
| 1990 | 21.8°C | 16.7°C | 11.7°C | 30.6°C | 7.7°C | 41 mm | 66% | 3.7 m/s | 5.4 |
| 1989 | 21.5°C | 17.3°C | 13.2°C | 26.8°C | 9.9°C | 27 mm | 68% | 3.7 m/s | 5.2 |
| 1988 | 20.8°C | 17.0°C | 13.3°C | 27.6°C | 9.1°C | 33 mm | 73% | 3.8 m/s | 5.4 |
| 1987 | 23.1°C | 17.8°C | 12.5°C | 29.1°C | 8.6°C | 21 mm | 64% | 4 m/s | 5.8 |
| 1986 | 19.8°C | 15.9°C | 12.0°C | 26.0°C | 9.2°C | 28 mm | 77% | 3.3 m/s | 5.1 |
| 1985 | 21.9°C | 17.2°C | 12.5°C | 27.8°C | 9.3°C | 49 mm | 69% | 4.1 m/s | 5.5 |
| 1984 | 21.1°C | 16.4°C | 11.7°C | 25.5°C | 9.3°C | 51 mm | 66% | 3.9 m/s | 5.9 |
| 1983 | 21.3°C | 17.4°C | 13.4°C | 27.8°C | 10.1°C | 48 mm | 74% | 4.1 m/s | — |
| 1982 | 21.3°C | 16.7°C | 12.1°C | 27.7°C | 8.3°C | 62 mm | 69% | 4.1 m/s | — |
| 1981 | 21.1°C | 17.0°C | 12.9°C | 27.5°C | 8.2°C | 17 mm | 74% | 3.6 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 21.2°C with lows near 12.6°C (mean 16.9°C), based on 45 years of NASA POWER data.
September averages 37 mm of rainfall in Port Denison, about average for rainfall. The wettest on record was 71 mm in 2014.
The hottest September reached 33.6°C in 2023. The coldest dipped to 6.8°C in 2004.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 0.9°C. Daytime highs moved from 21.3°C to 22.5°C and overnight lows from 12.5°C to 13.2°C over the same span.
September is one of the cooler months of the year in Port Denison and about average for rainfall, so plan for around 21.2°C daytime highs and 12.6°C at night.
Not quite — September is the 4th coolest month in Port Denison, averaging 16.9°C.
For September in Port Denison, pack light layers you can adjust through the day, with typical highs of 21.2°C and lows of 12.6°C.
Relative humidity in September averages 70% — moderately humid.
Average wind speed in September is 4 m/s. The windiest September on record averaged 4.5 m/s (2012).
The wettest September on record was 2014 with 71 mm. On average, September sees 37 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 Port Denison 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.
