September is one of the cooler months of the year in New Plymouth, with average highs near 13.5°C and lows around 8.1°C (mean 10.8°C). It is about average for rainfall, averaging 112 mm of rainfall and 86% relative humidity across the period.
September is one of the cooler months of the year in New Plymouth. Across 45 years of records, the warmest September in New Plymouth was 2005 — when the month averaged 12°C — while the coldest was 1992 at 8.8°C. Typical September days reach 13.5°C with nights near 8.1°C. The long-term September temperature trend is broadly flat.
September is about average for rainfall in New Plymouth, averaging 112 mm of rainfall. The wettest September on record was 2010 with 215 mm, while the driest was 2001 at 25 mm.
Relative humidity in New Plymouth during September averages 86%. The most humid September was 1988 at 89%, and the least humid was 1985 at 83%.
September receives about 3.7 kWh/m²/day of solar energy in New Plymouth. The sunniest September was 1985 at 4.2 kWh/m²/day, and the cloudiest was 2016 at 3.2.
Average wind speed in New Plymouth during September is 4.4 m/s. The windiest September was 2010 at 5.5 m/s, while the calmest was 1989 at 3.5 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 11.0°C | 10.2°C | 11.0°C | 10.9°C | 11.0°C | 0°C |
| Avg High | 13.8°C | 12.8°C | 13.9°C | 13.5°C | 13.6°C | -0.2°C |
| Avg Low | 8.2°C | 7.5°C | 8.2°C | 8.3°C | 8.4°C | +0.2°C |
| Avg Rain | 94 mm | 124 mm | 93 mm | 118 mm | 142 mm | +48 mm |
September temperatures in New Plymouth have stayed relatively stable across the record.
September has ranged from a record low of 0.8°C (2009) to a record high of 19°C (1989).
Rainfall in September is about average for rainfall, averaging 112 mm, with a wettest year of 215 mm.
A quieter season to visit New Plymouth
If your dates are flexible, the more temperate months of February and January tend to be the most comfortable for visiting New Plymouth. That said, September — with days averaging 13.5°C and nights around 8.1°C (mean 10.8°C) and higher rainfall (112 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 | 13.6°C | 11.1°C | 8.7°C | 16.2°C | 3.4°C | 134 mm | 86% | 5.2 m/s | 3.6 |
| 2024 | 13.6°C | 11.0°C | 8.5°C | 16.0°C | 4.1°C | 126 mm | 87% | 4.5 m/s | 3.7 |
| 2023 | 14.4°C | 11.6°C | 8.8°C | 17.1°C | 4.9°C | 169 mm | 88% | 4.7 m/s | 3.8 |
| 2022 | 13.8°C | 11.2°C | 8.7°C | 16.5°C | 3.8°C | 140 mm | 86% | 3.7 m/s | 3.5 |
| 2021 | 13.0°C | 10.4°C | 7.8°C | 15.4°C | 3.7°C | 153 mm | 85% | 4.7 m/s | 3.8 |
| 2020 | 13.1°C | 10.6°C | 8.0°C | 15.7°C | 1.2°C | 130 mm | 86% | 5 m/s | 3.8 |
| 2019 | 13.5°C | 10.7°C | 8.0°C | 17.1°C | 5.1°C | 141 mm | 87% | 4.4 m/s | 3.7 |
| 2018 | 13.5°C | 10.8°C | 8.1°C | 18.0°C | 4.5°C | 49 mm | 86% | 4.4 m/s | 4 |
| 2017 | 13.4°C | 11.1°C | 8.8°C | 16.2°C | 5.6°C | 156 mm | 88% | 4.6 m/s | 3.5 |
| 2016 | 14.3°C | 11.6°C | 9.0°C | 17.0°C | 4.2°C | 126 mm | 88% | 4.3 m/s | 3.2 |
| 2015 | 12.6°C | 10.1°C | 7.5°C | 15.0°C | 4.1°C | 90 mm | 85% | 4.4 m/s | 3.8 |
| 2014 | 14.2°C | 11.3°C | 8.4°C | 17.3°C | 3.8°C | 122 mm | 86% | 4.4 m/s | 3.9 |
| 2013 | 13.8°C | 11.1°C | 8.5°C | 17.0°C | 2.2°C | 115 mm | 85% | 5 m/s | 3.7 |
| 2012 | 13.4°C | 10.8°C | 8.2°C | 18.1°C | 4.1°C | 96 mm | 83% | 4.9 m/s | 3.7 |
| 2011 | 12.8°C | 10.1°C | 7.4°C | 16.6°C | 4.4°C | 72 mm | 85% | 3.9 m/s | 4 |
| 2010 🌧️ | 13.4°C | 11.1°C | 8.9°C | 16.0°C | 5.7°C | 215 mm | 87% | 5.5 m/s | 3.3 |
| 2009 | 14.1°C | 10.7°C | 7.4°C | 15.7°C | 0.8°C | 109 mm | 86% | 3.6 m/s | 3.9 |
| 2008 | 13.8°C | 11.1°C | 8.4°C | 16.2°C | 4.9°C | 89 mm | 87% | 4 m/s | 3.8 |
| 2007 | 13.8°C | 10.8°C | 7.9°C | 18.3°C | 2.6°C | 47 mm | 86% | 3.6 m/s | 3.7 |
| 2006 | 13.9°C | 11.3°C | 8.8°C | 16.4°C | 3.6°C | 36 mm | 87% | 3.7 m/s | 3.6 |
| 2005 🔥 | 15.1°C | 12.0°C | 8.9°C | 18.3°C | 4.7°C | 87 mm | 85% | 3.7 m/s | 3.9 |
| 2004 | 12.7°C | 9.8°C | 6.9°C | 14.5°C | 2.9°C | 105 mm | 85% | 4.9 m/s | 3.6 |
| 2003 | 14.0°C | 11.4°C | 8.8°C | 17.2°C | 5.1°C | 199 mm | 87% | 5.2 m/s | 3.4 |
| 2002 | 13.6°C | 11.2°C | 8.7°C | 15.6°C | 3.7°C | 130 mm | 85% | 5.1 m/s | 3.4 |
| 2001 | 14.7°C | 11.4°C | 8.2°C | 16.6°C | 3.5°C | 25 mm | 83% | 3.7 m/s | 3.9 |
| 2000 | 13.7°C | 10.7°C | 7.8°C | 16.1°C | 3.2°C | 100 mm | 85% | 4.2 m/s | 3.6 |
| 1999 | 14.1°C | 11.0°C | 7.9°C | 16.4°C | 2.3°C | 79 mm | 86% | 3.8 m/s | 3.9 |
| 1998 | 14.2°C | 11.3°C | 8.3°C | 17.0°C | 4.4°C | 83 mm | 85% | 4.2 m/s | 3.8 |
| 1997 | 13.1°C | 10.0°C | 6.8°C | 15.4°C | 1.8°C | 91 mm | 86% | 4.5 m/s | 3.7 |
| 1996 | 14.1°C | 11.3°C | 8.4°C | 18.7°C | 3.5°C | 137 mm | 88% | 4 m/s | 3.6 |
| 1995 | 13.0°C | 10.6°C | 8.2°C | 16.3°C | 3.1°C | 149 mm | 89% | 4.1 m/s | 3.5 |
| 1994 | 11.8°C | 9.6°C | 7.4°C | 13.6°C | 4.2°C | 168 mm | 88% | 4.7 m/s | 3.7 |
| 1993 | 11.8°C | 9.2°C | 6.6°C | 15.8°C | 2.6°C | 131 mm | 85% | 4.2 m/s | 3.7 |
| 1992 ❄️ | 11.1°C | 8.8°C | 6.4°C | 14.2°C | 2.6°C | 194 mm | 88% | 4 m/s | 3.9 |
| 1991 | 12.8°C | 10.6°C | 8.4°C | 15.7°C | 3.9°C | 121 mm | 88% | 4.3 m/s | 3.7 |
| 1990 | 12.3°C | 9.6°C | 7.0°C | 14.5°C | 2.6°C | 83 mm | 85% | 3.8 m/s | 4.1 |
| 1989 | 15.3°C | 11.6°C | 8.0°C | 19.0°C | 1.0°C | 42 mm | 85% | 3.5 m/s | 4 |
| 1988 | 14.0°C | 11.5°C | 9.1°C | 18.8°C | 3.8°C | 105 mm | 89% | 4.5 m/s | 3.3 |
| 1987 | 13.3°C | 10.9°C | 8.5°C | 16.2°C | 3.7°C | 95 mm | 85% | 5 m/s | 3.7 |
| 1986 | 13.2°C | 10.6°C | 7.9°C | 16.4°C | 1.8°C | 108 mm | 86% | 4.5 m/s | 3.8 |
| 1985 | 14.2°C | 11.1°C | 8.0°C | 17.0°C | 3.7°C | 74 mm | 83% | 4.7 m/s | 4.2 |
| 1984 | 14.0°C | 10.7°C | 7.4°C | 16.9°C | 4.0°C | 74 mm | 84% | 4.1 m/s | 3.9 |
| 1983 | 13.9°C | 11.3°C | 8.8°C | 16.0°C | 3.8°C | 143 mm | 86% | 4.8 m/s | — |
| 1982 | 13.4°C | 10.5°C | 7.6°C | 15.7°C | 2.3°C | 100 mm | 86% | 3.9 m/s | — |
| 1981 | 13.1°C | 10.7°C | 8.3°C | 15.4°C | 3.7°C | 103 mm | 86% | 5.4 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 13.5°C with lows near 8.1°C (mean 10.8°C), based on 45 years of NASA POWER data.
September averages 112 mm of rainfall in New Plymouth, about average for rainfall. The wettest on record was 215 mm in 2010.
The hottest September reached 19°C in 1989. The coldest dipped to 0.8°C in 2009.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 0.2°C. Daytime highs moved from 13.7°C to 13.7°C and overnight lows from 8°C to 8.5°C over the same span.
September is one of the cooler months of the year in New Plymouth and about average for rainfall, so plan for around 13.5°C daytime highs and 8.1°C at night.
Not quite — September is the 4th coolest month in New Plymouth, averaging 10.8°C.
For September in New Plymouth, pack light layers you can adjust through the day, with typical highs of 13.5°C and lows of 8.1°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 86% — quite humid.
Average wind speed in September is 4.4 m/s. The windiest September on record averaged 5.5 m/s (2010).
The wettest September on record was 2010 with 215 mm. On average, September sees 112 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 New Plymouth 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.
