September is one of the cooler months of the year in Byron Bay, with average highs near 21.1°C and lows around 17.9°C (mean 19.5°C). It is one of the drier months, averaging 42 mm of rainfall and 72% relative humidity across the period.
September is one of the cooler months of the year in Byron Bay. Across 45 years of records, the warmest Septembers in Byron Bay were 2003 and 2013 — when the month averaged 20.7°C — while the coldest was 1990 at 18.1°C. Typical September days reach 21.1°C with nights near 17.9°C. The long-term trend is warming, about 0.3°C per decade.
September is one of the drier months in Byron Bay, averaging 42 mm of rainfall. The wettest September on record was 1988 with 151 mm, while the driest was 1991 at 2 mm.
Relative humidity in Byron Bay during September averages 72%. The most humid September was 2008 at 77%, and the least humid was 1991 at 62%.
September receives about 5.2 kWh/m²/day of solar energy in Byron Bay. The sunniest Septembers were 2003 and 2017 at 5.9 kWh/m²/day, and the cloudiest was 2010 at 4.
Average wind speed in Byron Bay during September is 5.5 m/s. The windiest Septembers were 2008 and 2021 at 6.1 m/s, while the calmest was 1987 at 4.1 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 19.0°C | 19.1°C | 19.8°C | 19.7°C | 19.9°C | +0.9°C |
| Avg High | 20.7°C | 20.8°C | 21.4°C | 21.2°C | 21.3°C | +0.6°C |
| Avg Low | 17.3°C | 17.4°C | 18.2°C | 18.1°C | 18.5°C | +1.2°C |
| Avg Rain | 56 mm | 45 mm | 40 mm | 33 mm | 34 mm | -22 mm |
September temperatures in Byron Bay have risen by about 1°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 11.1°C (1987) to a record high of 27.1°C (2003).
Rainfall in September is one of the drier months, averaging 42 mm, with a wettest year of 151 mm.
One of the best times to visit Byron Bay
September is one of the best times to visit Byron Bay. Expect days averaging 21.1°C and nights around 17.9°C (mean 19.5°C) — cooler than Byron Bay's yearly average — with moderate rainfall (42 mm), so conditions are generally comfortable for sightseeing and outdoor plans.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 21.4°C | 20.1°C | 18.7°C | 23.7°C | 15.9°C | 8 mm | 74% | 4.9 m/s | 5.4 |
| 2024 | 22.1°C | 20.6°C | 19.1°C | 26.5°C | 16.2°C | 82 mm | 73% | 5.9 m/s | 5.1 |
| 2023 | 21.6°C | 20.3°C | 18.9°C | 26.1°C | 17.2°C | 11 mm | 71% | 5.4 m/s | 5.3 |
| 2022 | 20.6°C | 19.3°C | 17.9°C | 24.0°C | 16.5°C | 71 mm | 75% | 5.6 m/s | 4.4 |
| 2021 | 20.9°C | 19.3°C | 17.7°C | 24.4°C | 14.9°C | 16 mm | 71% | 6.1 m/s | 5.3 |
| 2020 | 21.0°C | 19.8°C | 18.7°C | 24.0°C | 15.5°C | 15 mm | 73% | 5.3 m/s | 5 |
| 2019 | 21.0°C | 19.4°C | 17.7°C | 24.1°C | 14.9°C | 8 mm | 72% | 5.2 m/s | 5.6 |
| 2018 | 20.6°C | 19.4°C | 18.1°C | 23.4°C | 16.6°C | 77 mm | 73% | 5.8 m/s | 4.8 |
| 2017 | 22.3°C | 20.3°C | 18.3°C | 26.6°C | 14.3°C | 5 mm | 69% | 5.7 m/s | 5.9 |
| 2016 | 21.6°C | 20.0°C | 18.5°C | 24.0°C | 15.9°C | 27 mm | 72% | 5.6 m/s | 4.8 |
| 2015 | 20.7°C | 19.1°C | 17.6°C | 24.2°C | 15.1°C | 44 mm | 71% | 5.5 m/s | 5 |
| 2014 | 20.4°C | 19.0°C | 17.5°C | 23.3°C | 13.6°C | 28 mm | 72% | 5.2 m/s | 5.3 |
| 2013 | 22.2°C | 20.7°C | 19.1°C | 24.9°C | 17.3°C | 35 mm | 74% | 5.5 m/s | 5.5 |
| 2012 | 20.8°C | 19.3°C | 17.8°C | 24.7°C | 13.8°C | 11 mm | 72% | 5.1 m/s | 5.6 |
| 2011 | 20.8°C | 19.1°C | 17.4°C | 25.5°C | 12.7°C | 23 mm | 70% | 5.3 m/s | 5.4 |
| 2010 | 21.8°C | 20.4°C | 19.0°C | 24.0°C | 17.3°C | 69 mm | 74% | 5.2 m/s | 4 |
| 2009 | 22.0°C | 20.4°C | 18.8°C | 25.4°C | 15.4°C | 22 mm | 68% | 5 m/s | 5.8 |
| 2008 | 20.6°C | 19.3°C | 18.1°C | 23.7°C | 15.6°C | 65 mm | 77% | 6.1 m/s | 5 |
| 2007 | 21.3°C | 19.7°C | 18.1°C | 25.2°C | 15.9°C | 53 mm | 74% | 5.6 m/s | 5.4 |
| 2006 | 20.4°C | 19.3°C | 18.1°C | 22.4°C | 15.0°C | 118 mm | 76% | 5.9 m/s | 5.3 |
| 2005 | 21.0°C | 19.5°C | 18.1°C | 24.2°C | 14.2°C | 43 mm | 72% | 5.9 m/s | 5.1 |
| 2004 | 21.1°C | 19.7°C | 18.2°C | 24.1°C | 15.7°C | 46 mm | 71% | 5.7 m/s | 5.3 |
| 2003 🔥 | 23.0°C | 20.7°C | 18.5°C | 27.1°C | 16.2°C | 4 mm | 67% | 6 m/s | 5.9 |
| 2002 | 21.9°C | 20.2°C | 18.6°C | 24.6°C | 15.0°C | 21 mm | 72% | 5.9 m/s | 5.4 |
| 2001 | 20.6°C | 19.3°C | 17.9°C | 22.7°C | 16.3°C | 24 mm | 72% | 5.1 m/s | 4.9 |
| 2000 | 21.6°C | 19.8°C | 18.0°C | 25.2°C | 15.3°C | 5 mm | 73% | 6 m/s | 5.6 |
| 1999 | 20.4°C | 19.3°C | 18.1°C | 22.8°C | 16.2°C | 58 mm | 74% | 5 m/s | 5 |
| 1998 | 21.6°C | 20.3°C | 19.0°C | 24.2°C | 15.9°C | 117 mm | 74% | 5.2 m/s | 4.7 |
| 1997 | 20.9°C | 19.4°C | 17.9°C | 26.0°C | 16.3°C | 54 mm | 75% | 5.5 m/s | 4.9 |
| 1996 | 21.1°C | 18.8°C | 16.5°C | 23.9°C | 12.1°C | 28 mm | 72% | 5.7 m/s | 5.5 |
| 1995 | 20.9°C | 19.2°C | 17.6°C | 24.0°C | 11.3°C | 33 mm | 74% | 5.6 m/s | 5.2 |
| 1994 | 20.6°C | 18.5°C | 16.4°C | 25.2°C | 13.0°C | 22 mm | 67% | 5.4 m/s | 5.7 |
| 1993 | 20.2°C | 18.9°C | 17.5°C | 25.4°C | 15.0°C | 56 mm | 70% | 5.4 m/s | 4.9 |
| 1992 | 20.9°C | 18.9°C | 17.0°C | 25.7°C | 12.0°C | 38 mm | 68% | 5.5 m/s | 5.4 |
| 1991 | 21.7°C | 19.6°C | 17.4°C | 26.7°C | 13.5°C | 2 mm | 62% | 5.2 m/s | 5.8 |
| 1990 ❄️ | 19.5°C | 18.1°C | 16.7°C | 22.6°C | 13.0°C | 38 mm | 71% | 5.5 m/s | 5 |
| 1989 | 20.3°C | 18.4°C | 16.4°C | 24.4°C | 13.9°C | 11 mm | 70% | 5.7 m/s | 5.6 |
| 1988 🌧️ | 21.0°C | 19.6°C | 18.1°C | 24.5°C | 13.7°C | 151 mm | 76% | 5.8 m/s | 4.9 |
| 1987 | 20.5°C | 18.7°C | 17.0°C | 24.4°C | 11.1°C | 3 mm | 69% | 4.1 m/s | 5.6 |
| 1986 | 21.1°C | 19.5°C | 17.8°C | 24.1°C | 14.4°C | 21 mm | 71% | 5.7 m/s | 5.3 |
| 1985 | 20.2°C | 18.6°C | 17.1°C | 24.8°C | 11.9°C | 72 mm | 72% | 5.1 m/s | 5.2 |
| 1984 | 20.3°C | 18.2°C | 16.2°C | 22.1°C | 13.2°C | 35 mm | 67% | 5.2 m/s | 5.6 |
| 1983 | 21.6°C | 20.0°C | 18.3°C | 25.6°C | 16.3°C | 67 mm | 76% | 5.5 m/s | — |
| 1982 | 20.0°C | 18.3°C | 16.6°C | 24.7°C | 13.0°C | 134 mm | 73% | 5.5 m/s | — |
| 1981 | 21.3°C | 19.6°C | 18.0°C | 26.5°C | 11.7°C | 11 mm | 71% | 4.8 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 21.1°C with lows near 17.9°C (mean 19.5°C), based on 45 years of NASA POWER data.
September averages 42 mm of rainfall in Byron Bay, one of the drier months. The wettest on record was 151 mm in 1988.
The hottest September reached 27.1°C in 2003. The coldest dipped to 11.1°C in 1987.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 1°C. Daytime highs moved from 20.7°C to 21.3°C and overnight lows from 17.2°C to 18.5°C over the same span.
September is one of the cooler months of the year in Byron Bay and one of the drier months, so plan for around 21.1°C daytime highs and 17.9°C at night.
Not quite — September is the 4th coolest month in Byron Bay, averaging 19.5°C.
For September in Byron Bay, pack light layers you can adjust through the day, with typical highs of 21.1°C and lows of 17.9°C.
Relative humidity in September averages 72% — moderately humid.
Average wind speed in September is 5.5 m/s. The windiest September on record averaged 6.1 m/s (2008).
The wettest September on record was 1988 with 151 mm. On average, September sees 42 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 Byron Bay 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.
